Rule2025-22565
Air Plan Approval; South Carolina; Second Planning Period Regional Haze Plan
Primary source
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Published
December 11, 2025
Effective
January 12, 2026
Issuing agencies
Environmental Protection AgencyNational Oceanic and Atmospheric Administration
Abstract
The Environmental Protection Agency (EPA) is approving a regional haze State Implementation Plan (SIP) revision submitted by the State of South Carolina on March 3, 2022 (hereinafter referred to as "Haze Plan"), as satisfying applicable requirements under the Clean Air Act ("CAA" or "Act") and EPA's Regional Haze Rule (RHR) for the regional haze program's second planning period. South Carolina's SIP submission was submitted to address the requirement that states must periodically revise their long-term strategies (LTSs) for making reasonable progress toward the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility, including regional haze, in mandatory Class I Federal areas (hereinafter referred to as "Class I areas"). This SIP submission also addresses other applicable requirements for the second planning period of the regional haze program. EPA is taking this action pursuant to sections 110 and 169A of the Act.
Full Text
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<title>Federal Register, Volume 90 Issue 236 (Thursday, December 11, 2025)</title>
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[Federal Register Volume 90, Number 236 (Thursday, December 11, 2025)]
[Rules and Regulations]
[Pages 57636-57674]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-22565]
[[Page 57635]]
Vol. 90
Thursday,
No. 236
December 11, 2025
Part V
Environmental Protection Agency
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40 CFR Part 52
Air Plan Approval; South Carolina; Second Planning Period Regional Haze
Plan; Final Rule
Federal Register / Vol. 90, No. 236 / Thursday, December 11, 2025 /
Rules and Regulations
[[Page 57636]]
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ENVIRONMENTAL PROTECTION AGENCY
National Oceanic and Atmospheric Administration
40 CFR Part 52
[EPA-R04-OAR-2022-0367; FRL-10406-02-R4]
Air Plan Approval; South Carolina; Second Planning Period
Regional Haze Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is approving a
regional haze State Implementation Plan (SIP) revision submitted by the
State of South Carolina on March 3, 2022 (hereinafter referred to as
``Haze Plan''), as satisfying applicable requirements under the Clean
Air Act (``CAA'' or ``Act'') and EPA's Regional Haze Rule (RHR) for the
regional haze program's second planning period. South Carolina's SIP
submission was submitted to address the requirement that states must
periodically revise their long-term strategies (LTSs) for making
reasonable progress toward the national goal of preventing any future,
and remedying any existing, anthropogenic impairment of visibility,
including regional haze, in mandatory Class I Federal areas
(hereinafter referred to as ``Class I areas''). This SIP submission
also addresses other applicable requirements for the second planning
period of the regional haze program. EPA is taking this action pursuant
to sections 110 and 169A of the Act.
DATES: This rule is effective January 12, 2026.
ADDRESSES: EPA has established a docket for this action under Docket
Identification No. EPA-R04-OAR-2022-0367. All documents in the docket
are listed on the <a href="http://regulations.gov">regulations.gov</a> website. Although listed in the
index, some information may not be publicly available, i.e.,
Confidential Business Information or other information whose disclosure
is restricted by statute. Certain other material, such as copyrighted
material, is not placed on the internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available either electronically through <a href="http://www.regulations.gov">www.regulations.gov</a> or in hard
copy at the Air Regulatory Management Section, Air Planning and
Implementation Branch, Air and Radiation Division, U.S. Environmental
Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia
30303-8960. EPA requests that if at all possible, you contact the
person listed in the FOR FURTHER INFORMATION CONTACT section to
schedule your inspection. The Regional Office's official hours of
business are Monday through Friday 8:30 a.m. to 4:30 p.m., excluding
Federal holidays.
FOR FURTHER INFORMATION CONTACT: Matthew Bloemer, Multi-Air Pollutant
Coordination Section, Air Planning and Implementation Branch, Air and
Radiation Division, Region 4, U.S. Environmental Protection Agency, 61
Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is
(404) 562-9653. Mr. Bloemer can also be reached via electronic mail at
<a href="/cdn-cgi/l/email-protection#51333d3e343c34237f3c302525393426113421307f363e27"><span class="__cf_email__" data-cfemail="98faf4f7fdf5fdeab6f5f9ececf0fdefd8fde8f9b6fff7ee">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
I. Background
On March 3, 2022, the South Carolina Department of Health and
Environmental Control (DHEC) \1\ submitted a revision to its SIP to
address regional haze for the second planning period.\2\ South Carolina
made this SIP submission to satisfy the requirements of the CAA's
regional haze program pursuant to CAA sections 169A and 169B and 40
Code of Federal Regulations (CFR) 51.308. EPA has determined that the
regional haze SIP revision for the second planning period meets the
applicable statutory and regulatory requirements and is thus approving
South Carolina's submission.
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\1\ On July 1, 2024, DHEC was restructured into a health agency,
the Department of Public Health, and an environmental agency, the
Department of Environmental Services (DES). In a letter dated June
20, 2024, South Carolina represented to EPA that all the functions,
powers, and duties of the environmental divisions, offices, and
programs of DHEC, including the authority to administer and enforce
state implementation plans, are retained and continued in full force
and effect under DES. The letter is in the docket for this
rulemaking. The state agency will simply be referred to as ``the
State'' or ``South Carolina'' for the remainder of this document.
\2\ The March 3, 2022, SIP submission, with exception of the
supporting modeling files and Confidential Business Information, is
included in the docket for this rulemaking.
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Through a notice of proposed rulemaking (NPRM) published on July
31, 2025 (90 FR 36005), EPA proposed to approve South Carolina's Haze
Plan as satisfying the regional haze requirements for the second
planning period contained in the CAA and 40 CFR 51.308. EPA described
its rationale for proposing to approve the Haze Plan in the July 31,
2025, NPRM. Comments on the July 31, 2025, NPRM were due on or before
September 29, 2025.
II. Response to Comments
In response to the NPRM, EPA received one set of comments from the
National Parks Conservation Association (NPCA), Sierra Club, and the
Coalition to Protect America's National Parks (hereinafter
``Conservation Groups''); one set of comments from the Mid-Atlantic/
Northeast Visibility Union (MANE-VU); and one set of comments from the
Augusta Aiken Audubon Society, Coalition to Protect America's National
Parks, NPCA, South Carolina Environmental Law Project, and Waccamaw
Audubon Society. Additionally, EPA received a comment letter from an
anonymous commenter about greenhouse gases \3\ that is not relevant to
this action, and two identical comments in support of this action from
one individual. All comments received are available in the docket for
this rulemaking. Summaries of the significant comments received and
EPA's responses to these comments are below.
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\3\ Specifically, the commenter asks EPA to ``account for the
economic costs of carbon dioxide'' in this action. However,
greenhouse gases are non-haze forming and are therefore beyond the
scope of this action, which is focused solely on visibility
impairing pollutants and specifically the approvability of South
Carolina's regional haze SIP for the second planning period. Nor
does the commenter identify any legal duty for EPA to calculate such
costs. The commenter cites to Executive Order 13990 as authority,
but that executive order was revoked on January 20, 2025. The
commenter also cites generally to the National Environmental Policy
Act (``NEPA''), but it is long-settled that NEPA does not apply to
EPA's actions approving SIPs. See Appalachian Power Co. v. EPA, 477
F.2d 495, 508 (4th Cir. 1973) (quoting the holding in Getty Oil Co.
(Eastern Operations), Inc. v. Ruckelshaus, 467 F.2d 349, 359 (3d
Cir. 1972) that ``[it] is apparent that the Clean Air Act itself
contains sufficient provisions for the achievement of those goals
sought to be attained by NEPA'').
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Comment 1: The Conservation Groups claim that EPA's new uniform
rate of progress (URP) policy violates the CAA. These comments are
discussed in more detail in Comments 1.a through 1.d. A response to
these comments follows after Comment 1.d.
First, the Conservation Groups assert that EPA recently announced a
new policy whereby if ``visibility conditions for a Class I area
impacted by a State are below the URP and the State has evaluated
potential control measures and considered the four statutory factors,
the State will have presumptively demonstrated reasonable progress for
the second planning period.'' However, they state EPA's description of
the new policy in its proposal to approve South Carolina's 2022 SIP
Revision differs from earlier descriptions of the policy as originally
announced in the Agency's proposal to
[[Page 57637]]
approve West Virginia's SIP. They state that in the West Virginia
proposal, EPA explained that, if visibility conditions at affected
Class I areas \4\ are projected to be below the URP, and the state
considered the four factors, the state presumptively demonstrates
reasonable progress and that absent from EPA's description of the new
URP policy in the West Virginia proposal is a need for states to have
``evaluate[d] potential control measures.'' The Conservation Groups
assert that in EPA's proposal here, EPA incorporates this additional
phrase into its description of the new URP policy for the first time,
without explaining the significance of that purported change.
Additionally, they state that EPA explicitly states that the new policy
reflects only ``a change in policy from current guidance as to how the
URP should be used in the evaluation of regional haze second planning
period SIPs.''
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\4\ Areas statutorily designated as mandatory Federal Class I
areas consist of national parks exceeding 6,000 acres, wilderness
areas and national memorial parks exceeding 5,000 acres, and all
international parks that were in existence on August 7, 1977. CAA
section 162(a). There are 156 mandatory Class I areas. The list of
areas to which the requirements of the visibility protection program
apply is in 40 CFR part 81, subpart D.
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Response 1: EPA disagrees with the Conservation Groups. EPA has not
substantively changed the URP policy since it was announced in the West
Virginia regional haze NPRM,\5\ including in the South Carolina
regional haze NPRM. In the South Carolina regional haze NPRM, EPA noted
that ``it is the Agency's policy, as announced in the recent proposed
action for West Virginia's Regional Haze SIP for the second planning
period, that, where visibility conditions for a Class I area impacted
by a State are below the URP and the State has evaluated potential
control measures and considered the four statutory factors, the State
will have presumptively demonstrated reasonable progress for the second
planning period for that area.'' Although the Conservation Groups are
correct that EPA included the phrase ``has evaluated potential control
measures'' within this sentence and that EPA did not include this
phrase in the West Virginia NPRM when discussing the URP Policy, the
inclusion of this phrase was merely descriptive and was not intended to
announce any substantive deviation from EPA's URP policy. This is
because evaluation of potential control measures for regional haze SIPs
is conducted pursuant to the four factors. Specifically, the RHR text
at 40 CFR 308(f)(2)(i) requires states to evaluate and determine the
emission reduction measures that are necessary to make reasonable
progress by considering the four statutory factors. Additionally, the
full sentence quoted by the Conservation Groups in the South Carolina
regional haze NPRM clearly indicates that it was merely summarizing the
``Agency's policy, as announced in the recent proposed action for West
Virginia's Regional Haze SIP.'' EPA confirms that the URP policy is as
follows: where visibility conditions for a Class I area impacted by a
State are below the URP and the State has considered the four statutory
factors, the State will have presumptively demonstrated reasonable
progress for the second planning period for that area.
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\5\ See 90 FR 16478 (April 18, 2025).
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Comment 1.a: The Conservation Groups state that EPA's URP policy
violates the plain language of the CAA. They quote Loper-Bright
Enterprises v. Raimondo for the proposition that ``a statutory
provision is interpreted `using the traditional tools of statutory
construction' to arrive at the provision's `best reading.' '' \6\ They
state that the starting point for that inquiry is the text of the Act
and then assert that the plain language of 42 U.S.C. 7491 bars EPA's
proposed new policy.
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\6\ 603 U.S. 369, 400, 403 (2024).
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The Conservation Groups note that section 7491(b)(2) requires
states to develop plans that ``make reasonable progress toward meeting
the national goal'' and that section 7491(g)(1) defines ``reasonable
progress,'' providing that, ``in determining reasonable progress there
shall be taken into consideration the costs of compliance, the time
necessary for compliance, and the energy and non-air quality
environmental impacts of compliance, and the remaining useful life of
any existing source subject to such requirements.'' They assert that
``the dependent clause `in determining reasonable progress' must be
joined with the independent clause of that section--i.e., the four
reasonable progress factors--to make sense.'' Thus, they suggest that
``accurately reading those clauses together, the Act requires that
states and EPA must determine what constitutes `reasonable progress'
based on the four statutory factors listed in Section 7491(g)(1)'' and
that ``absent from the statutory text is any reference to the URP.''
The Conservation Groups state that ``EPA misreads this provision
when, in its new URP policy, it changes the phrase `taken into
consideration' into `considers.' '' They maintain that ``[t]he word
`consideration' means `something that is considered as a ground of
opinion or action' or `the act of regarding or weighing carefully.' ''
The Conservation Groups state that ``the things that states and EPA
must `take into consideration' are the four statutory factors listed in
(g)(1).'' Furthermore, they assert that ``States and EPA must not
merely `consider' the four statutory factors, but must use them `in
determining reasonable progress,' confirming that the best reading of
this statutory provision requires states to determine reasonable
progress based on the four statutory factors, and not other unlisted
factors.'' They state that ``[h]ad Congress intended states to consider
other factors, such as the URP, in determining what constitutes
reasonable progress, it would have listed those factors in the
statutory definition for `reasonable progress.' ''
The Conservation Groups also assert that ``[t]he new URP policy
also would only require states and EPA to apply the Act's text in
certain scenarios'' and that ``[u]nder the new policy, even if a state
conducted control analyses that show new or existing controls are
reasonable based on the four statutory factors, states and EPA can
ignore the results of those analyses and not require any emission
reduction measures to make reasonable progress if they show all
affected Class I areas are projected to be below the URP glidepath at
the end of the planning period.'' They state that this would result in
EPA and states ``disregard[ing] the text that Congress set forth in
section 7491(g)(1) requiring states to determine reasonable progress
based on the four statutory factors. A policy that makes the statutory
text superfluous in some cases, but not in others, is absurd.''
The Conservation Groups claim that EPA's proposal for South
Carolina approval is a prime example. They note that ``South Carolina
requested that EPA approve the 2022 SIP Revision without incorporating
into the SIP any of the permit provisions the State determined were
necessary to make reasonable progress--a request EPA proposes to
grant.'' However, they assert that ``EPA ignores that, in the 2022 SIP
Revision, South Carolina determined that installation of wet flue gas
desulfurization (wet FGD) on [International Paper--Georgetown's (IP-
Georgetown)] No. 1 Recovery Boiler would cost just $3,100/ton of
[sulfur dioxide (SO<INF>2</INF>)] reduce,'' which the Conservation
Groups suggest is a cost-effective control. South Carolina stated that
the $3,100/ton value was no longer applicable, and rejected this
potential control measure, because IP Georgetown had requested a
federally enforceable limit on the Boiler's potential to emit of
[[Page 57638]]
330 [tons per year (tpy)] of SO<INF>2</INF> to be incorporated into the
SIP. Thus, they state that ``[b]ecause EPA proposes to grant South
Carolina's request to exclude this limit from the SIP, the State's
reason for rejecting wet FGD for the No. 1 Recovery Boiler is no longer
valid. Yet, South Carolina and EPA still exclude wet FGD for the No. 1
Recovery Boiler despite the fact that South Carolina's own Four-Factor
Analysis for IP Georgetown shows that this control is reasonable and
cost-effective, and so, necessary to make reasonable progress for the
facility, because they allege that all Class I areas affected by South
Carolina pollution are projected to be below the URP glidepath.'' The
Conservation Groups then claim that ``[a]s a result, the new URP policy
allows EPA and states to disregard the text that Congress set forth in
section 7491(g)(1) requiring states to determine reasonable progress
based on the four statutory factors. A policy that makes the statutory
text superfluous in some cases, but not in others, is absurd.''
The Conservation Groups then note that ``[m]ultiple courts,
including the Supreme Court, have held that the Clean Air Act's plain
text requires that EPA engage in rigorous and substantive review of
SIPs.'' They quote section 7491(b)(2)(B), which requires states to
develop plans ``that mak[e] reasonable progress toward meeting the
national goal'' and assert that this ``inherently requires EPA to
assess whether SIP submissions provide adequate measures to achieve
that goal.'' They also quote section 7410(k)(3), which requires EPA to
determine if SIPs ``meet all of the applicable requirements of this
chapter,'' and argue that this provision requires EPA to ``assess the
adequacy, effectiveness, and reasonableness of SIPs to ensure they
comply with the Act and its implementing regulations.''
The Conservation Groups assert that ``EPA's new URP policy would
render these Clean Air Act requirements superfluous. In pointing to the
new policy, EPA tries to evade its duty to review Four-Factor Analyses
or control determinations to ensure that the technical bases for those
analyses are adequately documented and the determinations are based on
reasoned decision-making.'' They assert that the South Carolina
proposal here is an apt example and note that ``EPA's entire evaluation
of South Carolina's Four-Factor Analyses spans just two pages of the
proposal, one of which is devoted just to describing its new URP
policy.'' They maintain that ``[i]n its purported `evaluation,' EPA
merely makes conclusory statements that what South Carolina did in the
2022 SIP Revision was `reasonable' without providing any explanations
or analyses to support those statements.'' The Conservation Groups
state that ``EPA states that South Carolina `reasonably' concluded that
no new controls are necessary for [Century Aluminum of South Carolina
Inc. (Century)].'' But they assert that ``[t]he only support EPA
provides for that assertion is a bare claim that South Carolina
evaluated the cost of controls consistent with the Control Cost Manual,
but nowhere in the proposal does EPA explain how South Carolina's
analyses complied with that Manual or whether the cost information used
in the analyses was reliable or adequately documented.'' On the other
hand, the Conservation Groups state that ``readily available record
evidence, including the Conservation Groups comments to the State on
its draft 2022 SIP Revision, show that South Carolina neither followed
the Control Cost Manual nor provided necessary documentation to support
its analyses.'' They allege that ``[r]ather than provide any rationale
to support its assertions or grapple with the record before it, EPA
points to its new URP policy to claim that South Carolina's control
determinations for Century are reasonable and the 2022 SIP Revision
presumptively demonstrated reasonable progress for the second planning
period.''
In addition, the Conservation Groups state that ``EPA's claim that
the Act requires only reasonable progress and not maximal progress is a
red herring'' and ``[t]he plain text of the Clean Air Act embodies
Congress's determination that the rate of progress achieved by the
emission reduction measures found to be reasonable based on the four
statutory factors `is, by definition, a reasonable rate of progress.'
'' They argue that ``EPA tries to sever the word `reasonable' from
`progress' in justifying its new URP policy to make a free-floating
determination, unmoored from the four statutory factors, as to what is
`reasonable.' '' On the contrary, the Conservation Groups maintain that
``in severing `reasonable' from ``progress'' here, EPA must also
recognize the ordinary meaning of the word `progress,' which is defined
as `gradual betterment' or `a forward or onward movement.' '' Thus,
they assert that the ``Agency cannot use its attempt to break this term
apart to justify approving SIPs that improperly adopt the status quo
instead of requiring facilities to adopt emission reduction measures
that are reasonable based on a review of the four factors, and
therefore, necessary to make reasonable progress toward the goal of
remedying existing and preventing future impairment. In any event, the
Agency cannot change the fact that Congress deliberately placed
`reasonable progress' under section 7491(g)'s heading of `Definitions,'
making it a statutorily defined term.''
The Conservation Groups allege that ``EPA's own interpretation of
the Act's text in its 2017 RHR revision preamble demonstrates that the
new URP policy violates the statute.'' From the preamble, they state
that ``EPA explained that the terms `compliance' and `subject to such
requirements' in section 7491(g)(1) showed that `Congress intended the
relevant determination to be the requirements with which sources would
have to comply in order to satisfy the [Clean Air Act's] reasonable
progress mandate.' '' Thus, they argue that ``the Four-Factor Analyses
must be the basis on which states determine the requirements that
represent reasonable progress.''
The Conservation Groups state that EPA cannot point to any asserted
ambiguity or lack of explicit direction in 7491(g)(1) to claim it can
interpret the statutory text to allow consideration of visibility
conditions or the URP in determining what constitutes reasonable
progress. Instead, they claim, ``every tool'' available must be used
``to determine the best reading of the statute and resolve the
ambiguity.''
The Conservation Groups assert that ``EPA also cannot escape Loper-
Bright's mandate to find the `best reading' of the provision by citing
Congress' instruction for EPA in section 7491(a)(4) to issue
regulations as some indication of intent to delegate authority to EPA
to undercut the Regional Haze Program'' and ``nothing in section
7491(a)(4) authorizes EPA to create a `presumption' that a haze plan
demonstrates reasonable progress, thereby excusing the state from
implementing reasonable emission reductions based on a consideration of
the statutory factors for a source, where affected Class I areas are on
or below the URP.'' They further argue that ``section 7491(a)(4)
authorizes EPA only to `promulgate regulations' `after notice and
public hearing.' '' Therefore, they allege that ``in a transparent
attempt to avoid actually issuing any uniform, national ``regulation''
under sections 7491(a)(4) and 7607(d)(1)(J) articulating the Agency's
interpretation of the Clean Air Act's visibility provisions, EPA is
instead attempting to amend the RHR on a piecemeal, state-by-state
basis.'' Moreover, they maintain that ``EPA has failed to comply with
section 7491(a)(4)'s mandate to issue any such regulation ``after
notice and public hearing.''
[[Page 57639]]
The Conservation Groups also assert that ``nothing in section 7491
suggests, let alone clearly states, that EPA has authority to create a
presumption that, where a Class I area is on the so-called URP, states
need not implement further emission reductions based on a consideration
of the four statutory reasonable factors.'' Finally, the Conservation
Groups state that ``under section 7491(a)(4), EPA must `promulgate
regulations to assure reasonable progress toward meeting the national
goal.' The national goal is `the prevention of any future, and the
remedying of any existing, impairment of visibility in mandatory class
I Federal areas which impairment results from manmade air pollution.'
''
The Conservation Groups claim that Congress directed states to make
reasonable progress in each successive planning period. They point to
section 7491(b)(2)(B), which provides that states' plans must set forth
long-term strategies ``for making reasonable progress toward meeting
the national goal'' covering ``ten to fifteen year'' periods. They
assert that the Act ``does not contemplate prolonging progress toward
attaining natural visibility conditions.'' The Conservation Groups
argue that Congress ``set a framework for EPA to establish iterative
planning periods during which states must build on emission reductions
achieved in each successive planning period.'' The Conservation Groups
then state that ``EPA claims in the proposal that it `believe[s] this
policy also recognizes the considerable improvements in visibility
impairment that have been made by a wide variety of state and federal
programs in recent decades.' '' They contend that ``[m]erely relying on
past reductions, or expected ongoing reductions from the implementation
of already existing air quality programs, again absurdly makes this
statutory text superfluous by allowing states and EPA to evade the
directive to continue making progress toward the natural visibility
goal in each planning period if the states show that all affected Class
I areas are projected to be below the URP at the end of the planning
period.'' They conclude that ``EPA relies on a factor that Congress
could not have intended that it or states consider.''
The Conservation Groups continue by stating ``[c]ontinued delay in
achieving the natural visibility goal is something Congress explicitly
addressed in the 1990 Clean Air Act amendments. Although the reasonable
progress provisions were enacted in the 1977 Amendments, EPA ignored
them. In response, Congress forced EPA to act with its 1990 Amendments
to the Act.'' Based on legislative history, the Conservation Groups
further assert that states and EPA must make reasonable progress toward
the natural visibility goal in each successive planning period.
Comment 1.b: The Conservation Groups assert that EPA's
contemporaneous understanding of the Act reflects the best reading of
the statute. The Conservation Groups cite Loper-Bright for the
proposition that ``an agency's contemporaneous understanding of a
statutory provision may warrant respect in interpreting that
provision.'' They assert that the RHR, as originally promulgated in
1999 ``is the best evidence of EPA's `contemporaneous' understanding of
the Clean Air Act's requirements.'' Quoting a provision of the 1999
RHR, they state that it ``required states and EPA to establish
reasonable progress goals (RPGs) based on the four statutory factors.''
The Conservation Groups acknowledge that the 1999 RHR also required
states to consider the URP in establishing RPGs but assert that
``nothing in the 1999 RHR regulatory text allows states or EPA to
ignore the requirement to determine the emission reduction measures
necessary to make reasonable progress based on the four statutory
factors.''
The Conservation Groups also note that ``[t]he 1999 RHR required
that, `[i]n determining whether the State's goal for visibility
improvement provides for reasonable progress towards natural visibility
conditions, the Administrator will evaluate the demonstrations
developed by the State pursuant to paragraphs (d)(1)(i) and (d)(1)(ii)
of this section.' The cross-referenced paragraphs pertain to the
state's demonstration of how the four factors were taken into
consideration in establishing the RPGs. Thus, neither EPA nor states
could treat the Four-Factor Analysis [(FFA)] required by the Act and
the RHR as an ungraded, make-work exercise.''
The Conservation Groups then quote that the 1999 RHR preamble and
assert that it ``made clear that states and EPA could not use the URP
to avoid complying with the statutory and regulatory requirements of
the haze program.'' The Conservation Groups also state that, ``in the
1999 RHR, EPA had originally proposed `presumptive `reasonable progress
targets,' similar to its new URP policy, which treats the URP as the
target states should aim for but not exceed in their SIPs. But EPA
ultimately rejected that approach in the final Rule.'' They conclude
that ``EPA rejected the notion that the URP itself necessarily
represented reasonable progress.'' The Conservation Groups cite to the
2017 RHR preamble, the 2019 Guidance,\7\ and the 2021 Clarifications
Memorandum \8\ to make similar arguments as stated above.
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\7\ In reference to EPA's August 20, 2019, guidance titled:
``Guidance on Regional Haze State Implementation Plans for the
Second Implementation Period'' (``2019 Guidance'') which is
available at: <a href="https://www.epa.gov/sites/default/files/2019-08/documents/8-20-2019_-_regional_haze_guidance_final_guidance.pdf">https://www.epa.gov/sites/default/files/2019-08/documents/8-20-2019_-_regional_haze_guidance_final_guidance.pdf</a>.
\8\ In reference to EPA's July 8, 2021, Clarification Memorandum
titled: ``Clarifications Regarding Regional Haze State
Implementation Plans for the Second Implementation Period'' (``2021
Clarification Memo'') which is available at: <a href="https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf">https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf</a>.
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The Conservation Groups state that ``[a]t every opportunity since
promulgating the original 1999 RHR, EPA has reaffirmed, reiterated, and
repeated that relying on the URP to avoid adopting otherwise reasonable
controls based on an analysis of the four statutory factors violates
the Clean Air Act. EPA's new URP policy allows states and EPA to do
exactly that, and so, cannot be the best reading of the statute.
Rather, EPA's contemporaneous interpretation of the Act embodied by the
1999 RHR constitutes the best reading of the Act's haze requirements.''
Comment 1.c: The Conservation Groups state that the context of the
Act's visibility provisions confirms the best reading of the statute.
Citing United States Sugar Corp. v. EPA, the Conservation Groups assert
that ``[t]he context of section 7491(g)(1) supports that EPA's
contemporaneous interpretation of the Act is the best reading of the
statute.'' They state that ``section 7491(g)(1) does not list
visibility conditions or the URP as factors that can be considered in
determining what constitutes reasonable progress'' whereas section
7491(g)(2), which defines Best Available Retrofit Technology (BART)
``explicitly includes visibility as one of its five factors.'' They
then quote Intel Corp. Inv. Pol'y Comm. v. Sulyma, for the proposition
that ``Congress acts intentionally and purposely when it includes
particular language in one section of a statute but omits it in
another.'' They assert that, ``[b]ecause Congress intentionally omitted
any reference to visibility in the definition of reasonable progress,
it is clear that states may not reject controls based on assertions
about visibility conditions at Class I areas.'' They then quote section
7491(b)(2) and assert that ``states and EPA account for visibility
impacts in determining which Class I areas are affected by in-state
pollution sources and in selecting the sources that contribute to
impairment at those Class
[[Page 57640]]
I areas to be addressed in the long-term strategy, but not in
determining what emission reduction measures are necessary to make
reasonable progress for those selected sources.''
The Conservation Groups next state that section 7491 ``does not
contain any exemptions from the Act's reasonable progress requirements,
including in cases where affected Class I areas are projected to be
below the glidepath.'' They assert that ``[t]his is again in stark
contrast to section 7491(c), which contains explicit exemptions from
BART that are based on visibility conditions. That Congress did not
provide for similar, or any, exemptions from reasonable progress shows
that Congress did not intend any exemptions such as EPA proposes
here.'' They further assert that ``EPA cannot create the exemption it
proposes by invoking the de minimis principle, as courts have explained
that `an agency can't use [that principle] to create an exception where
application of the literal terms would provide benefits, in the sense
of furthering the regulatory objectives.' ''
Finally, the Conservation Groups quote the 2017 RHR revision
preamble regarding the collective significance of small amounts of
pollutants to regional haze and conclude that ``under EPA's new URP
policy, states could evade the Act's reasonable progress requirements
even for large sources of visibility impairing pollution, for which
controls would likely result in large benefits.''
Comment 1.d: The Conservation Groups state that the purpose of the
Act's visibility provisions further confirms the best reading of the
statute. They cite Lissack v. Comm'r of Internal Revenue, and quoting
section 7491(a), the Conservation Groups assert that the purpose of the
Act's visibility provisions ``is the prevention of any future, and the
remedying of any existing, impairment of visibility in mandatory class
I Federal areas which impairment results from manmade air pollution.''
The Conservation Groups also quote the 2017 RHR revision preamble, in
which they assert ``EPA rejected the idea that states could use the URP
as a safe harbor, pointing to the Act's natural visibility goal.'' They
conclude that, ``[c]ontrary to Congress's stated goal in establishing
the Regional Haze Program, the new URP policy would allow states to
adopt SIPs that do not include any additional measures to remediate
anthropogenic visibility impairment during a given planning period.''
Response to Comments 1.a through 1.d: EPA disagrees with the
Conservation Groups' position that the URP policy articulated in our
proposed approval of South Carolina's submission is inconsistent with
the CAA. The Conservation Groups' reading of the statute is not the
best, and they misconstrue the recently adopted policy in several ways.
As noted by the Conservation Groups, under Loper Bright, courts seek to
determine the ``best reading'' of a statute. Loper Bright Enters. v.
Raimondo, 603 U.S. 369, 400 (2024).
First, EPA's recently adopted policy is consistent with the
statute. Pursuant to CAA section 169A(a)(4), Congress explicitly
delegated to EPA authority to promulgate regulations regarding
reasonable progress towards meeting the national goal. As the
Conservation Groups suggest, in determining the measures necessary to
make reasonable progress towards the national visibility goal under CAA
section 169A(a)(1), Congress mandated ``tak[ing] into consideration the
cost of compliance, the time necessary for compliance, and the energy
and nonair quality environmental impacts of compliance, and the
remaining useful life of any existing source subject to such
requirement.'' See CAA section 169A(g)(1).
But this does not mean, as the Conservation Groups incorrectly
state, that the recently adopted policy ignores the results of a
state's FFA if a Class I area is below the URP. Rather, consistent with
our discussion under the preamble of the 2017 RHR, the URP continues to
serve as a regulatory planning metric to inform states' decision making
when considering the four statutory factors. EPA disagrees with
Conservation Groups' view that the recently adopted URP policy is an
exemption to the statutory mandate; the policy continues to require
states to take into consideration the four statutory factors. Being
below the URP does not relieve a State of its obligations under the CAA
and the RHR to make reasonable progress. Also, EPA still reviews a
state's determination of whether additional control measures are
necessary for reasonable progress, whether the state submitted those
measures for incorporation into the SIP, and whether the measures are
consistent with other provisions in the CAA.
As required by the statute, South Carolina took into consideration
the four statutory factors in CAA section 169A(g)(1) and determined
that no additional controls were necessary to make reasonable progress.
CAA section 169A(b)(2) requires SIPs to include ``such emission limits,
schedules of compliance and other measures as may be necessary to make
reasonable progress.'' Congress explicitly stated its intent for states
to only include mechanisms as may be necessary for Class I areas to
achieve reasonable progress. South Carolina concluded that it was not
necessary to incorporate any new emission limitations, schedules of
compliance or other measures into its SIP. Thus, contrary to the
Conservation Groups' statements, South Carolina did not ignore the
results of its consideration of the four statutory factors.
Second, EPA disagrees with the Conservation Groups' statements that
EPA's recently adopted policy allows states and EPA to entirely ignore
the statutory directive to make reasonable progress toward the national
visibility goal in the second planning period. Due to the iterative
nature of the regional haze planning process, reasonable progress is
not measured solely through the accomplishments in any one, discreet
planning period. CAA section 169A(b)(2) requires SIPs to ``contain such
emission limits, schedules of compliance and other measures as may be
necessary to make reasonable progress'' toward the national visibility
goal and 169A(g)(1) requires that ``in determining reasonable progress
there shall be taken into consideration the cost of compliance, the
time necessary for compliance, and the remaining useful life of any
existing source subject to such requirements.'' Not only has the State
considered the four statutory factors and concluded that no additional
control measures would be appropriate considering the outcome of its
analysis, but the Class I areas affected by emissions from South
Carolina remain below their respective URPs. In doing so, the State has
adequately demonstrated that its current measures are all that are
necessary to make reasonable progress in the second planning period.
Third, regarding the Conservation Groups' statements that
``Congress set a framework for EPA to establish iterative planning
periods during which states must build on emission reductions achieved
in each successive planning period,'' there is no statutory or
regulatory requirement that this process must include a new set of
additional control measures each and every planning period. Not only is
the statute clear on its face, but the legislative history supports
EPA's reading of the CAA. The reconciliation report for the 1977 CAA
amendments indicates that the term ``maximum feasible progress'' in CAA
section 169A was changed to ``reasonable progress'' in the final
version of the legislation passed by both chambers. Therefore, a State
is required to determine only what constitutes
[[Page 57641]]
reasonable progress toward the national visibility goal under CAA
section 169A(a)(1), not achieve the maximal amount of visibility
improvement each iterative planning period. Under the 2017 RHR, a state
determines this by weighing and considering the four statutory factors
under CAA section 169A(g)(1) against potential additional control
measures to determine if any control measures are necessary for
reasonable progress. It is therefore reasonable that, after considering
the four statutory factors, South Carolina concluded that no additional
measures are necessary to make reasonable progress in this planning
period since the state's existing LTS is still making reasonable
progress at the Class I areas impacted by a state's anthropogenic
emissions and those Class I areas where South Carolina may be
reasonably anticipated to cause or contribute to any impairment.
Fourth, EPA's change in policy does not create an exemption, de
minimis or otherwise, from the statutory requirements. CAA Section 169A
requires any state that contains a Class I area, or ``which may
reasonably be anticipated to cause or contribute to any impairment of
visibility in any such area'' to have an implementation plan that
contains ``such emission limits, schedules of compliance and other
measures as may be necessary to make reasonable progress toward the
national goal'' of ``the prevention of any future, and the remedying of
any existing, impairment of visibility in mandatory class I Federal
areas which impairment results from manmade air pollution.'' See CAA
sections 169A(a), (b).
EPA's recently adopted policy does not create an exemption to these
statutory provisions. Under the policy, states are still required to
identify measures necessary to make reasonable progress by ``tak[ing]
into consideration'' the four statutory factors set forth in CAA
section 169A(g)(1), and to submit measures necessary for reasonable
progress to EPA to be reviewed for approvability into the SIP. A state
is not exempted from this requirement simply because a particular Class
I area is below the URP.
Both the CAA and the RHR then require the state to include those
measures in its SIP. CAA section 169A(b)(2); 40 CFR 51.308(f)(2).
However, regardless of whether the state identified additional measures
for inclusion in its SIP, if the state takes into consideration the
four factors, and the Class I areas the state contributes to are below
the URP, the state will be presumed to be achieving reasonable progress
towards the national goal for the second planning period with respect
to that area. At no point in the process of identifying measures
necessary to make reasonable progress toward the national goal does
this new policy exempt a state from its statutory and regulatory
obligations to identify measures necessary for reasonable progress by
taking into consideration the four statutory factors and including any
such measures in its SIP.
Fifth, the Conservation Groups incorrectly state that EPA's
recently adopted policy is contrary to the purpose of the statute. EPA
disagrees with that statement. The Conservation Groups failed to
consider the plain language of the statute in their assertion that
``[b]ecause Congress intentionally omitted any reference to visibility
in the definition of reasonable progress, it is clear that states may
not reject controls based on assertions about visibility conditions at
Class I areas.'' The Conservation Groups misconstrue why Congress
included in CAA section 169A(g)(2) an explicit requirement to consider
``improvement of visibility'' when determining BART but did not include
a parallel explicit requirement for the determination of reasonable
progress under CAA section 169A(g)(1).
CAA sections 169A(b)(2)(A) and (g)(7) make BART applicable to a
``major stationary source,'' with the potential to emit 250 tons of any
pollutant, that was in existence on August 7, 1977, but not ``in
operation'' before August 7, 1962, and whether or not the type or
quantity of that pollutant impacts visibility at any Class I area. The
BART provision outlined in CAA section 169A(b)(2)(A) thus demonstrates
Congressional intent for states to, first and foremost, focus attention
directly on the presumed sources of visibility impairment. Because
Congress directs states to look at specifically-identified (``BART
eligible'') \9\ sources, it was reasonable for Congress to also specify
that only those existing BART sources impacting visibility needed to be
subject to the five BART statutory factors in section 169A(g)(2)
(``Subject to BART''). See 70 FR 39104 at 39106-7 (July 6, 2005).
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\9\ See 40 CFR 51.301; 64 FR 35714 at 35738 (July 1, 1999); 70
FR 39104 at 39105 (July 6, 2005).
---------------------------------------------------------------------------
However, while the BART provisions mandate consideration of
visibility in determining which sources are subject to BART and in
selecting controls, the reasonable progress provisions make it optional
for non-BART sources.\10\ \11\ Specifically, there was no need to
insert a ``improvement in visibility'' provision with respect to CAA
section 169A(g)(1) since reasonable progress by definition includes
improvement in visibility. See CAA section 169A(a)(1). CAA section 169A
only ever speaks of reasonable progress in terms of making ``reasonable
progress toward meeting the national goal'' of CAA section 169A(a)(1)
of ``the prevention of any future, and the remedying of any existing,
impairment of visibility in mandatory class I Federal areas which
impairment results from manmade air pollution.'' See CAA sections
169A(a)(1), 169A(b)(2), and 169A(b)(2)(B). The only time the full
phrase ``reasonable progress toward meeting the national goal'' is
omitted is in CAA section 169A(g)(1), but it is clear from the three
other instances of the use of the term in CAA section 169A that the
best reading of that provision is that it is consistent with the three
other times Congress used the term ``reasonable progress'' in CAA
section 169A. Therefore, because visibility improvement is inherent in
determining what is necessary for reasonable progress, it was not
necessary for Congress to specifically add it to the reasonable
progress considerations in CAA section 169A(g)(1). The Conservation
Groups are therefore incorrect that EPA has attempted to ``escape''
Loper Bright's mandate to find the best reading of the statute; we
simply disagree with the Conservation Groups as to that best reading.
EPA has interpreted ``reasonable progress'' in section 169A(g)(1) in
light of the fact that that phrase clearly refers back to the three
other times it is used in full, that is, ``reasonable progress toward
meeting the national goal.'' Considering a phrase in light of its whole
statutory context, with a presumption that a phrase will be used
consistently throughout a statutory provision, is one of the canonical,
``traditional tools of statutory construction'' that Loper Bright
establishes as the judiciary's first stop in determining the best
reading of the statute. Loper Bright Enters. v. Raimondo, 603 U.S. 369,
399-401 (2024).
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\10\ See, e.g., 2019 Guidance at 36-37 (``EPA interprets the CAA
and the Regional Haze Rule to allow a state reasonable discretion to
consider the anticipated visibility benefits of an emission control
measure along with the other factors when determining whether a
measure is necessary to make reasonable progress.'').
\11\ EPA also notes that even in the first planning period,
States could consider visibility in their reasonable progress
determinations, so long as it was done in a reasonable way in
accordance with the CAA. See North Dakota v. U.S. E.P.A., 730 F.3d
750, 766 (8th Cir. 2013).
---------------------------------------------------------------------------
Lastly, the Conservation Groups incorrectly state that EPA's
application of the new policy is inconsistent with EPA's role under CAA
section 110(k)(3). Congress delegated EPA authority to
[[Page 57642]]
determine whether a SIP meets the requirements in CAA sections 169A and
169B. See CAA section 110(k)(3). The Conservation Groups assert that
EPA lacks ``authority'' to create a presumption because nothing in CAA
section 169A(a)(4) directs the Agency to create a presumption, and
furthermore, even if it did, the Agency did not follow the 169A(a)(4)'s
procedural requirements. The Conservation Groups misconstrue the role
of the Agency's URP Policy and the articulated presumption. The Policy
is not a regulation that states are required to follow. Rather, the
presumption discussed in the proposal explains the Agency's thinking in
reviewing states' second planning period SIPs. EPA is not only
authorized to review such SIPs but is in fact obligated to do so under
CAA section 110(k)(3). As such, the role of the Agency is not
ministerial, and the recently adopted policy does not exempt EPA from
meeting its statutory requirement. Thus, because South Carolina's SIP
meets the statutory and regulatory requirements, EPA concluded that
approval of South Carolina's SIP is reasonable.
Comment 2: The Conservation Groups state that ``[u]sing the
`traditional tools' of construction, EPA cannot square its new URP
policy with the RHR, just as it cannot square that policy with the
Clean Air Act.'' They further state that ``[t]he RHR's long-term
strategy requirements track those of the Clean Air Act, requiring that
such strategies `must include the enforceable emissions limitations,
compliance schedules, and other measures that are necessary to make
reasonable progress pursuant to [40 CFR 51.308(f)(2)(i) through (iv)].'
'' They assert that 40 CFR 51.308(f)(2)(i) requires states to evaluate
and determine the emission reduction measures that are necessary to
make reasonable progress by considering the four factors (costs of
compliance, the time necessary for compliance, the energy and non-air
quality environmental impacts of compliance, and the remaining useful
life of any potentially affected anthropogenic source of visibility
impairment) and suggest that 40 CFR 51.308(f)(2)(i) contains a
dependent clause (``the State must evaluate and determine . . . the
measures that are necessary to make reasonable progress'') to make
sense. Based on this grammatical argument, they state that ``accurately
reading these clauses together requires that states and EPA determine
the measures that must be included in a state's long-term strategy
based on the four factors'' (emphasis in original comments) and that
``[n]othing in sections 51.308(f)(2)(ii)-(iv) changes this requirement
or allows states to reject otherwise reasonable measures that satisfy
the four factors by pointing to the URP.''
The Conservation Groups claim that ``[t]he RHR's RPG provisions
further make clear that the URP cannot supplant the requirement to
conduct thorough and reasonable Four-Factor Analyses to identify
necessary measures in the long-term strategy. Section 51.308(f)(3)'s
requirement that states establish RPGs for their in-state Class I areas
refers back to (f)(2)'s requirement to establish emission limits and
other measures necessary to make reasonable progress.'' They further
state that ``section 51.308(f)(2) is directly linked to the four
factors, as the emission limits and measures necessary to make
reasonable progress must be based on the four factors.''
The Conservation Groups proceed to claim that ``[t]he purpose and
history of the 2017 RHR revision confirm these requirements. As EPA
explained in the 2017 RHR revision preamble, one purpose of the revised
Rule was to clarify misunderstandings in the interpretation and
application of the 1999 RHR.'' Citing to the 2017 RHR, they state that
EPA clarified that the URP is not and was never intended to be a ``safe
harbor.'' \12\ Furthermore, they claim that EPA declined to explicitly
state in the RHR itself that the URP is not a safe harbor because it
believed that point was already clear. Quoting the 1999 RHR, the
Conservation Groups likewise cite to language in which EPA stated that
``[t]he URP was never intended to be a safe harbor.'' \13\
---------------------------------------------------------------------------
\12\ See 82 FR 3093.
\13\ See 82 FR 3093-94.
---------------------------------------------------------------------------
The Conservation Groups state that EPA has ``explained that the
Four-Factor Analysis is not a box checking exercise; rather, states
must engage in thorough and reasoned analyses to satisfy the
requirements of the RHR'' and that ``[c]ontrary to EPA's new URP
policy, a state's mere mention or reference to the four statutory
factors is not sufficient to demonstrate that the state conducted those
analyses in compliance with the RHR.'' They further assert that ``EPA
has time and time again explained that treating the URP as a safe
harbor, as the Agency proposes to do with its new URP policy, violates
the RHR.''
The Conservation Groups conclude by stating that ``the text of the
RHR specifically requires EPA to engage in rigorous and substantive
reviews of state SIP submissions'' and suggest that ``EPA relies on the
new URP policy to evade its substantive review duties.''
Response 2: EPA disagrees with the Conservation Groups' position
that the URP policy is inconsistent with the RHR. This comment tracks
many of the issues the Conservation Groups raised with respect to their
allegations that EPA's recently adopted URP policy is inconsistent with
the CAA. For example, they assert that EPA's policy is inconsistent
with the regulatory requirement that the LTS ``must include the
enforceable emissions limitations, compliance schedules, and other
measures that are necessary to make reasonable progress'' and that this
policy allows states or EPA to reject otherwise reasonable emission
reduction measures that satisfy the four statutory factors based on the
URP. Just as the URP policy does not create an exemption to the CAA's
statutory provisions, it also does not create exemptions to the RHR.
Under the policy, and consistent with 40 CFR 51.308(f)(2), states are
still required to identify measures necessary to make reasonable
progress by considering the four statutory factors set forth in CAA
section 169A(g)(1), and to submit measures necessary for reasonable
progress to EPA to be reviewed for approvability into the SIP. A state
is not exempted from this requirement simply because a particular Class
I area is below the URP.
Both the CAA and the RHR then require the state to include those
measures in its SIP. CAA section 169A(b)(2); 40 CFR 51.308(f)(2).
However, regardless of whether the state identified additional measures
for inclusion in its SIP, if the state takes into consideration the
four factors, and the Class I areas the state contributes to are below
the URP, the state will be presumed to be achieving reasonable progress
towards the national goal for the second planning period with respect
to that area. At no point in the process of identifying measures
necessary to make reasonable progress toward the national goal does
this new policy exempt a state from its statutory and regulatory
obligations to identify measures necessary for reasonable progress by
taking into consideration the four statutory factors and including any
such measures in its SIP. We do not agree with the Conservation Groups
that the RHR's use of ``by considering'' with regard to the four
factors in 51.308(f)(2) means that the national goal of visibility and
a state's progress towards that goal is wholly excluded from a state
and EPA's consideration.
Because EPA's recently adopted policy is that there is a
presumption that
[[Page 57643]]
the state's second planning period SIP is making reasonable progress
for a Class I area, if the state has taken into consideration the four
statutory factors and that area is below the 2028 URP, EPA has
concluded that this SIP is fully approvable. To meet the RPG
requirements under 40 CFR 51.308(f)(3), the RPGs established by a state
must reflect the measures it deemed to be necessary to make reasonable
progress within the applicable implementation period and must be
projected to be achieved by the end of the applicable implementation
period. Therefore, it is sufficient under 40 CFR 51.308(f)(3) that this
SIP establishes RPGs that reflect visibility conditions that are
projected to be achieved by the end of the second planning period.
Comment 3: The Conservation Groups claim that ``[b]eyond violating
the plain language, intent, context, and purpose of both the Clean Air
Act and the RHR, EPA's application of its new URP policy in the
proposal here is both internally inconsistent and inadequately
explained. As a result, EPA fails to provide a `satisfactory
explanation' for its proposal to approve the 2022 SIP Revision, making
the proposal arbitrary and capricious in violation of both the CAA and
the APA.'' This comment, along with individual points raised by the
Conservation Groups, are summarized and responded to in Comments 3.a
and 3.b below.
Comment 3.a: The Conservation Groups state that EPA's proposal to
approve South Carolina's 2022 SIP Revision is internally inconsistent
in at least three ways. First, the Conservation Groups state that ``EPA
claims that its new URP policy does not treat the URP as a safe harbor;
yet EPA's statements explaining its new policy underscore that it
does.'' They state that this is contrary to the 1999 RHR, 2017 RHR
revision, 2019 Guidance, and 2021 Clarification Memo which all state
that the URP is not a safe harbor. Furthermore, they state that ``if
EPA's new URP does not treat the URP as a safe harbor,'' then the
``Agency's explanation and application of its new policy in the
proposal is inconsistent and not adequately explained, all of which
also violates the Clean Air Act and fundamental principles of reasoned
agency decisionmaking.''
Second, the Conservation Groups state that ``EPA notes in the
proposal that states' source selection methods must be `reasonable' and
`reasonably explained' but fails to explain or address anywhere in the
proposal whether the new URP policy requires that states' Four-Factor
Analyses be based on reliable, reasonable, and well-documented
information.'' They claim that EPA's new URP policy therefore allows
the Agency and states to treat the FFAs as an ``ungraded box checking
exercise,'' in violation of the CAA and RHR. They state that this
further makes EPA's proposal here internally inconsistent, arbitrary,
and capricious, because states are required to conduct reasonable
source selection processes but then permitted to conduct unreasonable
and unsupported FFAs. They claim also that this makes EPA's new policy
irrational, as states are still required to select sources, consider a
``meaningful set'' of control measures, and conduct FFAs ``without any
requirement that this process affect the ultimate outcome of the SIP.''
Third, the Conservation Groups assert that ``EPA explains that all
measures that the State determines are necessary to make reasonable
progress must be included in the SIP but also states in the proposal
that permit measures that South Carolina determined are necessary are
now `moot' and do not need to be included in the SIP.'' The
Conservation Groups say that the proposal ``repeatedly states that
measures, new or existing, that are found to be necessary must be
included as federally enforceable SIP measures as required by 42 U.S.C.
7491(b)(2) and 40 CFR 51.308(f)(2).'' Despite this, they claim that
``[i]n the 2022 SIP Revision, South Carolina determined that existing
measures contained in permit provisions for Century, [Santee Cooper
Cross Generating Station (Cross), Santee Cooper Winyah Generating
Station (Winyah)], and IP Georgetown are necessary to make reasonable
progress and prevent future impairment in this second planning period,
and so, proposed to incorporate those permit provisions into the SIP.
Similarly, South Carolina again determined in the 2025 SIP Supplement
that updated permit provisions for Cross, Winyah, and IP Georgetown are
necessary to make reasonable progress, and so, proposed to incorporate
those permit provisions into the SIP. Yet, buried in a footnote in the
proposal, EPA now asserts that these permit provisions are `moot' and
that the Agency is not incorporating any permit provisions into the
SIP.''
The Conservation Groups conclude by saying that ``[n]othing in the
proposal or letters EPA cites from the State analyzes, let alone
demonstrates, that these permit provisions are no longer necessary to
make reasonable progress or prevent future impairment.'' They state in
the December 2024 letter EPA cites in which South Carolina withdrew the
permit provisions for Century from the SIP, that South Carolina
``explicitly explained that it was in the process of updating a
`standalone regional haze construction permit' for Century and that the
State would `submit the final construction permit in a supplement to
the final SIP as part of the request for materials proposed for
adopting into the regulatory portion of the South Carolina SIP.''' The
Conservation Groups note that ``EPA points only to its new URP policy
and South Carolina's request to approve the 2022 SIP Revision without
any permit provisions based on that new policy to support its refusal
to incorporate these measures into the SIP. Therefore, they state that
``EPA's application of its new URP policy here is both internally
inconsistent with its own explanations of the Clean Air Act's and RHR's
requirements and in violation of those same requirements.''
Response 3.a: As discussed in more detail in response to Comments
1.a through 1.d, EPA disagrees with the comment that the URP policy is
a ``safe harbor'' or an exemption to the RHR requirements. Being below
the URP does not relieve a state of its obligations under the RHR to
make reasonable progress.
Regarding the comment that EPA fails to explain or address anywhere
in the proposal whether the new URP policy requires that states' FFAs
be based on reliable, reasonable, and well-documented information, EPA
disagrees. The NPRM explained that ``40 CFR 51.308(f)(2)(iii) plays an
important function in requiring a state to document the technical basis
for its decision making so that the public and EPA can comprehend and
evaluate the information and analysis the state relied upon to
determine what emission reduction measures must be in place to make
reasonable progress.'' In the NPRM, EPA also explained that
``[r]egarding cost and engineering information, the State provided the
underlying cost calculations associated with the cost summaries in
Section 7.8 of the plan for Century, Cross, IP-Georgetown, and
[WestRock Charleston Kraft, LLC (WestRock-Charleston)], and the
proposed FFAs in Appendix G provide engineering analyses evaluating
potential new control measures.'' This technical data is also discussed
in more detail in Responses 11.b, 11.c, and 11.d.
EPA also disagrees with the Conservation Groups' assertion that
approval of the Haze Plan under the new URP policy without any of the
permit provisions is arbitrary, capricious, and an abuse of authority
and does not comply with the substantive requirements of the CAA and
RHR. EPA proposed to approve the Haze Plan without the permit
[[Page 57644]]
conditions, as requested by South Carolina in its June 4, 2025, letter,
based on the new URP policy.\14\ South Carolina considered the four
statutory factors for Century, IP-Georgetown, Cross, and Winyah in
technical analyses. Subsequently, South Carolina clarified in its June
4, 2025, letter that it is not necessary to include in the SIP any
final permit conditions for these evaluated facilities and that
statements appearing in South Carolina's submittal concerning existing
or additional measures are no longer applicable. In addition, South
Carolina never submitted its 2025 SIP Supplement, and it confirmed in
its June 4, 2025, letter that it does not intend to submit or include
final permit conditions for these facilities for incorporation into the
regulatory portion of the South Carolina SIP. As discussed in the NPRM,
because South Carolina considered the four statutory factors for these
facilities and visibility conditions at all Class I areas to which
South Carolina contributes are below the URP, South Carolina has
demonstrated that it has made reasonable progress for the second
planning period without any measures in the regulatory portion of the
SIP for these facilities.
---------------------------------------------------------------------------
\14\ South Carolina's letter states: ``The South Carolina
Department of Environmental Services (Department) is requesting a
full approval of the Regional Haze State Implementation Plan (SIP)
for South Carolina Class I Federal Areas for Second Planning Period
(2019-2028) submittal dated March 3, 2022 (SC-132) pursuant to the
policy announced in the Environmental Protection Agency's (EPA)
April 18, 2025, proposed approval of West Virginia's (90 FR 16478)
Regional Haze SIP and reaffirmed in the proposed approval of South
Dakota's Regional Haze SIP (90 FR 20425) on May 14, 2025. . . . per
the presently applicable EPA policy, South Carolina's SIP submittal
meets the requirements of the Clean Air Act (CAA) for demonstrating
reasonable progress towards the visibility goal; therefore, no
additional or existing measures need to be adopted into the SIP as
part of the long-term strategy for this planning period. As a
result, it is not necessary to include in the SIP any final permit
conditions for any of the evaluated facilities, and according to the
policy, Section 7.9 of the SIP, Appendix G-3 of the SIP, and
statements appearing in Section 7.8 of the SIP concerning existing
or additional measures are no longer applicable.''
---------------------------------------------------------------------------
Comment 3.b: The Conservation Groups claim that EPA fails to
adequately explain how the new URP policy creates only a
``Presumption'' that a SIP is approvable. They state the ``EPA asserts
in the proposal that its new URP policy does not create a safe harbor
but creates only a `presumption' that a SIP demonstrates reasonable
progress and is approvable.'' In general, they state ``a presumption
establishes a `legal inference or assumption that a fact exists,'
`unless the adversely affected party overcomes' the presumption with
other evidence.'' They claim that ``even if the new URP policy created
only a presumption that a SIP is approvable, the new policy still
violates the plain text of the Clean Air Act and the RHR, as well as
EPA's interpretations of the Act and Rule.'' Additionally, they claim
that ``EPA cannot point to any `clear congressional authorization' for
the authority to create a presumption that, where a Class I area is on
the so-called URP, states need not implement further emission
reductions based on a consideration of the four statutory reasonable
factors.'' They conclude by saying that ``[i]n any case, EPA cannot
cure the legal errors in the new policy by claiming the policy creates
only a presumption, and so, is somehow different than treating the URP
as a safe harbor.''
The Conservation Groups further claim that ``EPA does not explain
the operation of the purported presumption created by its new policy
anywhere in the proposal. As noted, the presumption appears to relieve
EPA of its duty to substantively review a State's control
determinations and Four-Factor Analyses where the Agency concludes that
the State has triggered that presumption. Otherwise, it is entirely
unclear what role the `presumption' serves in EPA's review of SIPs.''
Thus, the Conservation Groups maintain that ``the presumption created
by the new policy also relieves states of the obligation to demonstrate
reasonable progress in a manner that is reasonable and adequately
documented.'' They state that EPA proposes to relieve South Carolina of
those obligations here, and ``even though South Carolina determined
that existing measures are necessary to make reasonable progress and
prevent future impairment for Century, Cross, Winyah, and IP
Georgetown, EPA proposes to grant the State's request to exclude all of
those measures from the SIP based on its new URP policy. Treating the
new URP policy as a presumption is contrary to the burdens set forth in
the Clean Air Act and the RHR.'' They assert that ``[n]othing in the
statute or the RHR allows EPA to shift that burden off the states or
the Agency.''
The Conservation Groups continue by saying that ``if the new URP
policy does, in fact, create only a presumption that a SIP is
approvable, then there must be circumstances in which the presumption
can be overcome.'' They state that ``[n]owhere in the proposal,
however, does EPA articulate what those circumstances would be or
whether or not they are present for South Carolina's 2022 SIP
Revision.'' They assert that ``EPA's proposal here fails to provide
adequate notice of the Agency's rationales in support of its proposed
action.''
The Conservation Groups go on to describe three circumstances that
``potentially could overcome the new URP policy's presumption that a
SIP is approvable.'' The first circumstance raised by the Conservation
Groups ``is that all Class I areas affected by pollution from the
state--here, South Carolina--are not projected to be below the URP
glidepath at the end of the planning period. As discussed in detail
below, however, that circumstance is present here.'' The second
circumstance raised by the Conservation Groups is that a state
``entirely fails to evaluate potential control measures or consider the
four statutory factors for any sources or group of sources.'' The third
circumstance raised by the Conservation Groups is that ``although
states evaluated potential control measures and considered the four
statutory factors, they failed to do so reasonably or in compliance
with the requirements of the Clean Air Act and the RHR.''
Response 3.b: Initially, EPA disagrees with the Conservation
Groups' assertion that the URP policy creates a presumption that the
SIP is approvable. Rather, the new policy creates a presumption that
Class I areas are making reasonable progress. Furthermore, EPA
disagrees with the assertion that EPA has not clearly explained how its
new policy creates a presumption that Class I areas are making
reasonable progress. As first articulated in West Virginia's April 18,
2025, notice and reiterated in other actions, including this action,
where projected 2028 visibility conditions for a Class I area impacted
by a state are below the URP and the state has considered the four
statutory factors, the state will have presumptively demonstrated that
its LTS is adequate to make reasonable progress for the second planning
period for that area. Thus, EPA has articulated two requirements that
must be met for the presumption to be applicable. Furthermore, EPA
notes that just because a Class I area is below the URP does not mean
that a state is relieved of its obligations under the CAA and the RHR
to make reasonable progress, as well as a multitude of other rule
requirements that must be satisfied. In other words, the URP is not a
``safe harbor,'' as that phrase has sometimes been used, because EPA
still must review a state's determination whether additional control
measures are necessary to make reasonable progress, if control measures
are necessary, determine whether the state submitted those measures for
incorporation into the SIP, and evaluate whether the
[[Page 57645]]
measures are consistent with other provisions in the CAA, as EPA did
here in approving South Carolina's SIP. EPA is not required, in acting
on the state's submission, to speculate about what facts or
circumstances would necessitate a disapproval.
Comment 4: The Conservation Groups state that ``[t]he new URP
policy violates the Clean Air Act's procedural requirements, as it is
inconsistent with both national policy and actions taken on second
planning period SIPs by nearly every EPA region'' and that ``[t]he new
policy also effectively revises the RHR without complying with the
Act's rulemaking requirements and is intended to have national scope
and effect.'' This comment, along with individual points raised by the
Conservation Groups, are summarized and responded to in Comments 4.a
through 4.d below.
Comment 4.a: The Conservation Groups assert the while ``EPA
acknowledges that its new policy reflects `a change in policy'
regarding the URP,'' it ``ignores that its announcement of this change
in a regional SIP action, and continued application of that policy in
other regional SIP actions, including this one, violates the Clean Air
Act's requirements that SIP actions be consistent with national
policy.''
Citing the 1999 RHR and 2017 RHR, as well as its 2019 Guidance and
2021 Clarification Memo, the Conservation Groups state that ``EPA's new
URP policy is incompatible with its own longstanding policy that the
URP is not a safe harbor, and the mere fact that a Class I area is
projected to be on or below the URP glidepath does not allow states to
conduct unreasonable Four-Factor Analyses or ignore reasonable emission
reduction measures. Not only is this EPA's longstanding policy, it is
also the Agency's national policy.''
The Conservation Groups then quote CAA section 7601(a)(2)(A), which
requires EPA to ``assure fairness and uniformity in the criteria,
procedures, and policies applied'' in acting on SIPs and EPA's
consistency regulations at 40 CFR part 56. They allege that ``[b]ecause
EPA's proposed approval of the South Carolina 2022 SIP Revision is
based on an interpretation of the Clean Air Act that `varies from
national policy,' the Agency is required under 40 CFR 56.5(b) to obtain
the concurrence of the relevant EPA Headquarters Office before
finalizing the proposed approval. Yet, nothing in the record indicates
that the regional office obtained that concurrence.''
The Conservation Groups then cite 40 CFR 56.5(c) and EPA's 1975
``State Implementation Plans--Procedures for Approval/Disapproval
Actions, OAQPS No. 1.2-005A'' and state that ``the record includes no
reference to the Agency's SIP Review Guidelines, let alone indicates
that EPA complied with them.'' Additionally, they assert that
``[b]ecause EPA's proposal `would significantly affect emission control
regulations' or `have significant national policy implications,' a full
interagency review and concurrence is required.'' With respect to this
interagency review, the Conservation Groups state that ``Executive
Order 12,866 requires review by the Office of Management and Budget of
any `significant regulatory actions,' which includes actions that
`[r]aise novel legal or policy issues arising out of legal mandates.'
'' They state that ``the record shows no attempt at compliance,'' but
rather ``that EPA's proposal incorrectly states that compliance is not
required.
The Conservation Groups conclude that ``EPA cannot take action or
approve a SIP that violates applicable Clean Air Act requirements.''
They state that ``by applying the new URP policy that sharply departs
from national policy, EPA proposes to do just that. EPA's proposed
piecemeal approach to rewriting its national URP policy arbitrarily and
impermissibly `institutionalize[s] the kind of inconsistencies that
prompted Congress to enact' Sec. 7601(a)(2) in the first place.'' They
further note that ``[b]ecause EPA has failed to demonstrate that it
complied with the Agency's own consistency regulations, as required by
40 CFR 56.5, the Agency's proposed action is contrary to law.''
Citing 40 CFR 56.5(a), the Conservation Groups assert that along
with requiring consistency with national policy, EPA's regulations
require that EPA regional office SIP actions ``[a]re as consistent as
reasonably possible with the activities of'' [sic] other EPA regions''
in accordance with 42 U.S.C. 7601(a)(2)(A) in order to ``assure
fairness and uniformity in the criteria, procedures, and policies
applied by the various [EPA] regions in implementing and enforcing''
the Act. The Conservation Groups state that ``EPA's current proposal to
approve the 2022 SIP Revision based on its new URP policy is
inconsistent with SIP actions taken by nearly every other EPA region,
as well other EPA Region 4 actions, stating that `the URP . . . is not
a `safe harbor.' '' Due to this alleged inconsistency, the Conservation
Groups assert that EPA's proposed approval ``violates the Clean Air
Act's and its implementing regulations' requirements.''
Response 4.a: Under FCC v. Fox, an agency's change in policy is not
arbitrary and capricious if the agency acknowledges the change,
believes the new policy to be better than the one it replaces, and
``show[s] that there are good reasons for the new policy.'' See 556
U.S. 502, 515. EPA did not change the policy sub silentio, as it stated
its reasons for implementing this recently adopted policy. EPA
announced this change in the proposed approval of West Virginia's
regional haze SIP on April 18, 2025. See 90 FR 16478. In Section I,
What action is the EPA proposing? of that notice, EPA states that
``[b]ased on our change in policy discussed in section V of this
document, EPA proposes that West Virginia's regional haze SIP meets the
statutory and regulatory requirements for the regional haze second
planning period.'' EPA more fully articulated the substance of the
change in policy in Section V, The EPA's Rationale for Proposing
Approval, of that notice. Id. at 16482-84. As EPA explained in the
proposal for this action, the changed policy is prospective, which
addresses the primary concern in FCC v. Fox.
Additionally, EPA notes that the legislative history of CAA section
169A is consistent with the Agency's change in policy. The Agency has
articulated its rationale for this change, including that this change
``aligns with the purpose of the statute and RHR, which is achieving
`reasonable' progress, not maximal progress, toward Congress' natural
visibility goal.'' See 90 FR 36005, 36017 (July 31, 2025). The
reconciliation report for the 1977 CAA amendments, indicates that the
term ``maximum feasible progress'' in 169A was changed to ``reasonable
progress'' in the final version of the legislation passed by both
chambers. See Legislative History of the CAA Amendments of 1977 P.L.
95-95 (1977), H.R. Rep. No. 95-564, at 535. This change in the final
version of the statute indicates that Congress did not require SIPs to
contain measures to make the maximal possible progress towards the
national goal in each Haze SIP. Instead, Congress intended for Class I
areas to achieve a rate of progress that was reasonable, taking into
consideration the four statutory factors under CAA section 169A(g)(1).
Therefore, EPA's recently implemented policy is consistent with the
Congressional intent behind the original framing of CAA sections 169A.
EPA disagrees that its change in policy means that all its actions
on second planning period regional haze SIPs that pre-date its proposed
approval of the West Virginia second planning period submittal are
inconsistent with
[[Page 57646]]
the new policy. On April 18, 2025, EPA announced its policy regarding
the use of the URP in the context of determining reasonable progress.
On July 7, 2025, in EPA's final action approving the West Virginia
regional haze SIP for the second planning period articulated the
policy. See 90 FR 29737 (July 7, 2025). The recently adopted policy is
consistent with EPA's long-standing position that the URP is not a
``safe harbor.'' As stated in Responses 1 and 1.a through 1.d, EPA's
new policy establishes a presumption that the reasonable progress
requirements of the CAA and the RHR are met if the state has taken into
consideration the four statutory factors and the visibility impairment
for each Class I area is projected to be below the URP (i.e., the
``glidepath'') at the end of the applicable planning period. Unlike
treating the URP as a ``safe harbor,'' the policy does not exempt or
allow a state to evade the requirements of the CAA or the RHR. Treating
the URP as a ``safe harbor'' would exempt states from considering the
four statutory factors and would allow states to exclude measures
necessary for reasonable progress from the SIP. Simply stated, final
actions pre-dating the recent URP policy weighed the URP differently in
evaluating whether regional haze plans met the requirements of the CAA
and the RHR.
EPA acknowledges that under this policy, the URP informs EPA
actions on SIPs differently than previous actions, which may result in
a different conclusion. Under 40 CFR 51.308(f)(3)(i), RPGs are to be
established by a state that contains a Class I area to ``reflect the
visibility conditions that are projected to be achieved by the end of
the applicable implementation period as a result of those enforceable
emissions limitations, compliance schedules, and other measures
required under paragraph (f)(2) of this section that can be fully
implemented by the end of the applicable implementation period, as well
as the implementation of other requirements of the CAA.'' The change in
policy leaves this process intact. As before our change in policy, a
state must still identify ``enforceable emissions limitations,
compliance schedules, and other measures'' [40 CFR 51.308(f)(2)], by
taking into consideration the four statutory factors, and EPA will
approve any such measures that are submitted by the State as measures
necessary for reasonable progress as long as they are consistent with
other provisions of the CAA. States' only other obligation under 40 CFR
51.308(f)(3) applies only when the RPG for a Class I area affected by
emissions from the state is above the URP. In that case, states must
provide a robust demonstration ``that there are no additional emission
reduction measures for anthropogenic sources or groups of sources in
the State that may reasonably be anticipated to contribute to
visibility impairment in the Class I area that would be reasonable to
include in the long-term strategy.'' Because EPA's URP policy only
applies when a Class I area is below its URP, the new policy does not
impact this obligation either.
EPA's Regional Consistency regulations at 40 CFR part 56, and in
particular 40 CFR 56.5(a) and (b), are not relevant to this action. 40
CFR 56.5(a) requires, in relevant part, that ``[e]ach responsible
official in a Regional Office, including the Regional Administrator,
shall assure that actions taken under the act . . . [a]re as consistent
as reasonably possible with the activities of other Regional Offices.''
40 CFR 56.5(b) requires that a ``responsible official in a Regional
office shall seek concurrence from the appropriate EPA Headquarters
office on any interpretation of the Act, or rule, regulation, or
program directive when such interpretation may result in application of
the act or rule, regulation, or program directive that is inconsistent
with Agency policy'' (emphasis added). As EPA expressly indicated in
the proposal for this action the approval is consistent with the change
in Agency policy, first announced in Air Plan Approval; West Virginia;
Regional Haze State Implementation Plan for the Second Implementation
Period. 90 FR 16478 (April 18, 2025). Therefore, there is no obligation
under EPA's Regional Consistency regulations for anyone in the Region
to seek concurrence from EPA Headquarters to take action consistent
with EPA policy. For the same reason, this action is also consistent
with the actions of other EPA Regional Offices. The lack of relevance
of these regulations to this action accounts for the lack of materials
related to compliance with the Regional Consistency process in the
docket for this rulemaking. Finally, as noted below, this action is not
subject to E.O. 12866.
Comment 4.b: The Conservation Groups cite the preamble to the 2017
RHR, and they assert that there are two ways EPA's new URP policy
effectively revises the national RHR. First, the Conservation Groups
maintain that the new URP policy ``creates an exception to the national
RHR's categorical prohibition against relying on the URP as a safe
harbor from reasonable control measures.'' They further note that ``EPA
claims that the Clean Air Act and the RHR allow states to avoid control
measures that are reasonable under the four statutory factors, and so,
necessary to make reasonable progress where the state demonstrates that
affected Class I areas are meeting the URP.'' Thus, they allege that
``EPA has revised a rule that, as a matter of law, allows no
exceptions, into a rule that allows exceptions when (or where) EPA
decides that all affected Class I areas are meeting the URP.'' Second,
the Conservation Groups maintain that ``the proposed action changes the
applicability of the RHR's URP policy, making that national policy
inapplicable to South Carolina.'' They further argue that ``[t]he
proposed action thus amends the national, categorical URP policy to no
longer be national or categorical.''
The Conservation Groups cite CAA section 7491(a)(4) and claim that
EPA cannot support its attempt to effectively amend the RHR through
regional SIP actions. They state that ``this section requires EPA to
undergo a rulemaking process to promulgate regulations.''
The Conservation Groups further cite 7607(d)(1), as requiring ``the
`promulgation or revision of regulations under part C of subchapter I
of [the Act] (relating to prevention of significant deterioration of
air quality and protection of visibility)' to be carried out using the
procedures in Section 7607(d).'' They also state that ``[t]he [Clean
Air] Act's rulemaking procedures require that EPA include in the docket
all data, information, and documents related to the methodology for the
proposed revision, as well as an explanation of the major legal
interpretations underlying the rule.'' The Conservation Groups further
note that ``this action is subject to the requirement in Executive
Order 12,866 for interagency review by the Office of Management and
Budget; and in turn, the procedures in Section 7607(d) require EPA to
provide the results of such review in the docket prior to the date of
proposal and finalization.'' The Conservation Groups assert that EPA
has not followed these procedures.
Response 4.b: EPA does not agree that the new policy effectively
revises the RHR. Rather, as described in Response 2, the policy is
consistent with the existing RHR. Moreover, the requirements of CAA
section 307(d) apply only to specific enumerated types of actions under
the CAA and to ``such other actions as the Administrator may
determine.'' \15\ Actions on SIPs are not one of the enumerated
actions, and the Administrator has not determined that this action is
subject to 307(d) pursuant
[[Page 57647]]
to section 307(d)(1)(V). Therefore, the procedures in 307(d) do not
apply to this action.
---------------------------------------------------------------------------
\15\ See CAA section 307(d)(1).
---------------------------------------------------------------------------
Comment 4.c: The Conservation Groups cite the preamble to the 2017
RHR revision, in which ``EPA concluded that judicial review of the
Rule--including EPA's national policy position that the URP is not a
safe harbor against implementing reasonable control measures--should be
centralized in the D.C. Circuit.'' They then assert that, ``[e]ven if
the proposed action does not amend the nationally applicable RHR (it
does), EPA must publish a finding that the revisions to the Agency's
national Rule, which embodies its national URP policy are `based on a
determination of nationwide scope [and] effect.' '' \16\
---------------------------------------------------------------------------
\16\ Citing 42 U.S.C. 7607(b)(1).
---------------------------------------------------------------------------
The Conservation Groups discuss two recent U.S. Supreme Court
decisions that pertain to the effect of a ``determination of nationwide
scope and effect'' on venue, EPA v. Calumet Shreveport Refining, LLC et
al. (``Calumet''), No. 23-1229 (June 18, 2025) and Oklahoma et al. v.
EPA et al. (``Oklahoma''), No. 23-1067 (June 18, 2025). Citing to
Calumet, they assert that ``Here, the key driver of EPA's action is its
new URP policy. EPA gives no other `intensely factual' consideration
for proposing to approve South Carolina's 2022 SIP Revision despite
ample evidence that additional emission reduction measures are
necessary to make reasonable progress.'' They continue to state that
``[w]here EPA does purport to draw a conclusion regarding the State's
Four-Factor Analyses, EPA does so in a conclusory fashion without any
substantive review.'' Furthermore, they argue that ``EPA's new URP
policy allows EPA to evade fact-intensive review of a state's Four-
Factor Analyses, instead substituting a purely ministerial
determination as to whether the SIP submittal contains Four-Factor
Analyses, regardless of whether they are rational or supported by the
record.''
Again citing Calumet, the Conservation Groups state that `` `EPA
relies on determinations of nationwide scope or effect to reach a
presumptive resolution, those determinations qualify as the primary
driver of its decision,' and EPA's action is therefore based on a
determination of nationwide scope or effect. That is precisely what has
happened here: EPA has made a presumptive resolution of the issue of
whether South Carolina's 2022 SIP Revision makes reasonable progress.''
They maintain that ``the Agency's resolution of that central issue is
indisputably based on the Agency's new URP policy that purportedly
allows EPA to determine that the 2022 SIP Revision presumptively
demonstrates reasonable progress.'' The Conservation Groups continue to
state ``[t]hat there are particular facts that might cause EPA to
depart from this presumption (and which facts EPA does not even
specify) would be merely `peripheral.' Indeed, EPA has now proposed to
apply its new URP policy to approve multiple SIPs across EPA Regions
without any hint that any of those SIPs might fail the `presumption.'
'' They further state that EPA's new policy is ``based on the same
determinations of nationwide scope and effect'' that it made in the
2017 RHR revision.
The Conservation Groups acknowledge that the Supreme Court held
that ``EPA still has a role in deciding whether a regional action is
based on a determination of nationwide scope or effect. While in dicta
the Supreme Court theorized that it would be rare for EPA to fail to
make the determination of nationwide scope and effect despite it being
appropriate to do so, the Court only mentioned issue preservation as a
potential obstacle to reviewability of such a failure.'' They further
state that ``[t]he Act gives EPA discretion to make the determination
of nationwide scope and effect; in such a circumstance, it is arbitrary
and capricious for EPA to fail to explain why it is or is not
exercising that discretion.''
Response 4.c: The Conservation Groups' claim that EPA ``must''
publish a finding that this action is ``based on a determination of
nationwide scope [or] effect'' is unsupported and incorrect. Under CAA
section 307(b)(1),\17\ a petition for review of an action that is
``locally or regionally applicable may be filed only in the United
States Court of Appeals for the appropriate circuit,'' with one
exception: if (i) the action ``is based on a determination of
nationwide scope or effect'' and (ii) ``if in taking such action the
Administrator finds and publishes that such action is based on such a
determination,'' then any petition for review must be filed in the D.C.
Circuit. Thus, if a locally or regionally applicable action is ``based
on a determination of nationwide scope or effect,'' the CAA's venue
provision expressly grants the EPA Administrator complete discretion to
invoke, or decline to invoke, the exception to the general rule that
challenges be heard in the appropriate regional circuits. The Supreme
Court has recognized that ``[b]ecause the `nationwide scope or effect'
exception can apply only when `EPA so finds and publishes' that it
does, EPA can decide whether the exception is even potentially
relevant.'' As the D.C. Circuit has also stated, the ``EPA's decision
whether to make and publish a finding of nationwide scope or effect is
committed to the agency's discretion and thus is unreviewable.''
Although a court may review ``whether a locally or regionally
applicable action is based on a determination of nationwide scope or
effect when EPA so finds and publishes. . . . a court may not `second-
guess' the agency's discretionary decision to make and publish (or not)
a finding of nationwide scope or effect.''
---------------------------------------------------------------------------
\17\ See 42 U.S.C. 7607(b)(1).
---------------------------------------------------------------------------
The Administrator has not made and published a finding that this
action is based on a determination of nationwide scope or effect.
Accordingly, any petition for review of this action must be filed in
the United States Court of Appeals for the appropriate regional
circuit.
Comment 5: The Conservation Groups state that ``[e]ven if EPA's new
URP policy does not violate the Clean Air Act and RHR (it does), EPA
cannot approve South Carolina's 2022 SIP Revision based on that
policy.'' They further note that ``[a]s EPA explains in its proposal
here, to qualify for presumptive approval under the new policy, all
Class I areas, both in-state and out-of-state, that may be affected by
pollution from the state must be projected to be below their respective
URP glidepaths at the end of the planning period.'' The Conservation
Groups assert that ``[n]either EPA nor South Carolina demonstrate that
all Class I areas affected by South Carolina pollution will be below
their respective glidepaths in 2028.''
The Conservation Groups raise three individual reasons to justify
their assertion above. First, they claim all states rely on the
Interagency Monitoring of Protected Visual Environments (IMPROVE)
monitoring network to develop their URP glidepaths, but recent threats
raise significant concerns about the continued operation of the
network. Second, they claim neither EPA nor South Carolina clearly
states whether they relied on adjusted URP glidepaths, but to the
extent they do, those adjustments do not comply with the requirements
of the RHR. Third, they claim neither EPA nor South Carolina clearly
identifies the Class I areas that may be affected by pollution from
South Carolina, but to the extent they do, EPA and South Carolina both
ignore additional out-of-state Class I areas that
[[Page 57648]]
are affected by South Carolina pollution. Each of these points raised
are summarized and responded to in more detail in Comments 5.a through
5.c below.
Comment 5.a: The Conservation Groups note ``the importance of the
IMPROVE network to the Regional Haze Program (and other Clean Air Act
programs)'' and point out that ``the Trump Administration issued a
stop-work order on multiple contracts to maintain the IMPROVE network
earlier this year.'' They state that, ``[a]lthough those contracts
appear to have been reinstated, funding cuts for air quality monitoring
remains an issue, threatening the continued operation of the IMPROVE
network.'' The Conservation Groups conclude that ``[w]ithout the
IMPROVE network, not only would states be unable to meet the RHR's
monitoring requirements, but they also could not show that their SIPs
qualify for approval under EPA's new URP policy.''
Response 5.a: EPA disagrees that there are any issues with the
IMPROVE network that are relevant to our action on the Plan. From the
time that South Carolina worked on the Haze Plan up until it submitted
the Plan to EPA, the IMPROVE network was in operation. Additionally, as
stated in the Haze Plan, and required by the rule, South Carolina
continues to support and participate in the IMPROVE network. Concerns
about the future funding of the IMPROVE network are speculative, out of
the control of South Carolina, and beyond the scope of the basis for
our action on the Haze Plan.
Comment 5.b: The Conservation Groups cite the provisions of the RHR
concerning the URP and RPGs and note that ``neither EPA nor South
Carolina state whether they rely on adjusted or unadjusted
glidepaths.'' They provide further context by stating that ``[i]t
appears that [Visibility Improvement State and Tribal Association of
the Southeast (VISTAS)] relied on EPA's glidepath adjustments from the
Agency's September 2019 Modeling Technical Support Document (2019
Modeling TSD). In the VISTAS final Regional Haze Air Quality Report
(Final VISTAS Modeling Report), VISTAS explains that the URP can be
adjusted to account for the contribution of international anthropogenic
emissions on visibility impairment at Class I areas to derive a
`default adjusted' glidepath, citing EPA's 2018 Technical Guidance on
Tracking Visibility Projects for the Second Implementation Period of
the Regional Haze Program (2018 Visibility Tracking Guidance).''
The Conservation Groups assert that the ``VISTAS and EPA glidepath
adjustments fail to satisfy the requirements of the RHR'' because
``[i]n its 2019 Modeling TSD, EPA highlighted substantial problems with
available data and methods for adjusting Class I area glidepaths based
on both international and prescribed wildland fire emissions.''
Additionally, they state that ``EPA also noted that the science on
which modeling contributions from international emissions rests is
questionable, stating that `[d]ue to the uncertainty in many of the
calculations and modeling and ambient data, additional scrutiny of the
initial glidepath adjustments are warranted.' '' The Conservation
Groups note several data and modeling limitation for prescribed fires,
which include: limited existing emissions data and that data does not
``accurately'' capture the year-to-year variability with these
emissions; the categorization of fires between wildfires (considered
natural emissions) and prescribed fires (considered anthropogenic
emissions) is uncertain; and the impacts of prescribed fires are likely
double counted since they are already accounted for when estimating
conditions on 20 percent most impaired days. They state that EPA did
not include contributions from prescribed fire in its proposed
adjustments to the glidepath in the 2019 Modeling Technical Support
Document. Finally, they state that ``these adjustments allow EPA and
states to `flatten out' the glidepaths for the relevant Class I areas
to make it appear that these Class I areas are on track to meet the
Clean Air Act's goal of achieving natural visibility conditions when
that is not the case.''
Therefore, the Conservation Groups claim that ``[t]o the extent EPA
and South Carolina rely on VISTAS or EPA URP glidepath adjustments,
those adjustments do not satisfy the requirements of the RHR.'' They
conclude by saying that ``[n]either South Carolina nor EPA can properly
rely on URP adjustments that do not comply with the RHR'' and that
``EPA also cannot show that the South Carolina 2022 SIP Revision
satisfies the new URP policy for presumptive approval.''
Response 5.b: EPA disagrees with this comment. South Carolina used
an unadjusted value for ``natural visibility conditions on the most
impaired days.'' For example, at Cape Romain Wilderness Area (Cape
Romain), this value is 9.78 deciview (dv), as shown in Figure 3-1 of
South Carolina's Haze Plan. This value corresponds to the unadjusted
value for natural conditions at Cape Romain (9.78 dv) found in Appendix
A of EPA's June 3, 2020, ``Recommendation for the Use of Patched and
Substituted Data and Clarification of Data Completeness for Tracking
Visibility Progress for the Second Implementation Period of the
Regional Haze Program,'' \18\ which provides updates to EPA's December
20, 2018, ``Technical Guidance on Tracking Visibility Progress for the
Second Implementation Period of the Regional Haze Program,'' \19\ This
is further supported by information contained in Table 4-1 of the
``VISTAS Future Year Model Projections Report Task 9a'' found in
Appendix E-6 in South Carolina's Haze Plan. In this report, the
unadjusted value for natural conditions at Cape Romain is 9.79 dv,\20\
whereas the calculated adjusted value is 11.89 dv. Additionally, for
the nearby Class I areas outside of South Carolina, Okefenokee National
Wilderness Area (Okefenokee) and Wolf Island National Wilderness Area
(Wolf Island), which are impacted by emissions from sources in South
Carolina, Georgia also used unadjusted values for natural visibility
conditions in their glidepath analysis. Therefore, neither South
Carolina nor Georgia made adjustments to the glidepath for the Class I
areas impacted by sources in South Carolina, so the Conservation
Groups' concerns about hypothetical adjustments to the glidepath are
not relevant to the URP analysis being relied upon by EPA in this
action.
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\18\ See <a href="https://www.epa.gov/sites/default/files/2020-06/documents/memo_data_for_regional_haze_0.pdf">https://www.epa.gov/sites/default/files/2020-06/documents/memo_data_for_regional_haze_0.pdf</a>.
\19\ See <a href="https://www.epa.gov/sites/default/files/2018-12/documents/technical_guidance_tracking_visibility_progress.pdf">https://www.epa.gov/sites/default/files/2018-12/documents/technical_guidance_tracking_visibility_progress.pdf</a>.
\20\ The 9.79 dv value corresponds to the value in Appendix A of
EPA's 2018 ``Technical Guidance on Tracking Visibility Progress for
the Second Implementation Period of the Regional Haze Program,''
which was the guidance that was available at the time the VISTAS
Report in Appendix E-6 was developed. This value was revised to 9.78
in the updated 2020 EPA memorandum referenced above.
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Comment 5.c: The Conservation Groups cite CAA section 169A(b)(2),
and assert that ``[t]he Act requires states in which a Class I area is
located or `the emissions from which may reasonably be anticipated to
cause or contribute to any impairment of visibility in any such area'
to develop a SIP that makes reasonable progress toward the natural
visibility goal.'' They also state that similar language is found in 40
CFR 51.308(f), which says that states must address regional haze at all
in-state Class I areas ``and in each mandatory Class I Federal area
located outside the State that may be affected by emissions from within
the State.'' And finally, they cite the 2019 Guidance for the
[[Page 57649]]
same assertion. They state that ``[n]either South Carolina in the 2022
SIP Revision nor EPA in its proposal here clearly specify which out of
state Class I areas the State identified as being impacted by South
Carolina pollution.'' Therefore, the Conservation Groups claim that
South Carolina failed to satisfy the CAA requirement that the State
identify affected Class I areas, and EPA failed to adequately explain
the basis for its proposal to approve the states identification of
Class I areas.
The Conservation Groups further state that Table 10-3 and Figure
10-1 of South Carolina's submittal identifies the top 10 Class I areas
outside of South Carolina impacted by the State's projected 2028
emissions but that ``[n]either EPA nor South Carolina clearly state
whether any of the Class I areas listed in Table 10-3 or Figure 10-1 of
the 2022 SIP Revision are the Class I areas that South Carolina
identifies as being affected by-instate pollution.'' The Conservation
Groups thus contend that South Carolina did not ``satisfy the Clean Air
Act's requirement that it identify affected Class I areas'' and cite to
CAA section 169A(b)(2) and 40 CFR 51.308(f)(2) in support of this
statement.
The Conservation Groups also assert that ``even assuming South
Carolina identified the 10 Class I areas listed above, the State still
failed to properly identify all out-of-state Class I areas affected by
South Carolina pollution, and so, neither South Carolina nor EPA can
show that all affected Class I areas are projected to be below their
respective URP glidepaths at the end of the planning period.'' They
state that ``South Carolina relied on VISTAS modeling to identify
affected out-of-state Class I areas. However, the VISTAS modeling, and
South Carolina's identification of Class I areas based on that
modeling, is highly flawed.'' The Conservation Groups identify two
specific concerns with the VISTAS modeling and claim that the modeling
did not meet the Clean Air Act's requirements.
First, the Conservation Groups state that ``South Carolina
identified the Class I areas noted above based on its statewide
emissions of only SO<INF>2</INF> and [nitrogen oxides (NO<INF>X</INF>)]
and did not consider direct emissions of [particulate matter (PM)]''
and the State also did not ``consider other haze-forming pollutants,
like NH<INF>3</INF> and VOCs.'' On that account, they argue that
``South Carolina failed to consider all emissions of visibility
impairing pollutants in identifying affected Class I areas.'' They
further highlight that ``South Carolina identified only the `top 10
Class I areas outside of South Carolina' that are affected by pollution
from the State.'' However, the Conservation Groups argue that ``neither
the Clean Air Act nor the RHR allow states to identify only the most or
top impacted Class I areas, or otherwise set a cutoff for the
identification of affected Class I areas'' and that ``[b]oth the
statute and the regulation require states to identify any Class I area
to which a state contributes to any impairment.'' They maintain that
the ``[c]ontrolling precedent mandates that words like `any' must be
given their literal, `capacious' meanings'' and that ``[t]he plain
language of the Act mandates that EPA and the states broadly identify
all Class I areas to which in-state pollution may contribute to
visibility impairment, and not some subset of those states.'' On that
account, the Conservation Groups assert that ``EPA's own summary of
South Carolina's identification of affected Class I areas shows that
the State's process did not meet requirements of the Clean Air Act.''
Second, the Conservation Groups claim that ``the VISTAS modeling
was riddled with errors and inaccuracies, rendering that modeling
highly unreliable.'' They state that the VISTAS modeling significantly
underpredicted the contribution of sulfate to visibility impairment on
the 20 percent most impaired days, that it relied on data that ``did
not reflect the dramatic shift in nitrate contribution to visibility
impairment over the five-year period representing current conditions
from 2014 to 2018.'' The Conservation Groups continue by claiming that
VISTAS' Particulate Matter Source Apportionment Technology (PSAT)
tagging process was flawed and that VISTAS applied PSAT tagging to
sulfate and nitrate separately, even though those pollutants act in
combination with other haze pollutants to cause visibility impairment.
They conclude that ``[a]s a result, the VISTAS modeling arbitrarily and
incorrectly excluded large sources of SO<INF>2</INF> and
NO<INF>X</INF>, thereby likely ignoring out-of-state Class I areas that
are affected by South Carolina pollution sources.''
The Conservation Groups claim that ``even the flawed VISTAS
modeling on which South Carolina relied to identify affected Class I
areas shows that South Carolina pollution contributes to impairment at
numerous Class I areas that the State and EPA ignore.'' Furthermore,
they state that ``VISTAS PSAT modeling results in the 2022 SIP Revision
appendices show that South Carolina sulfate and nitrate pollution
contributes to impairment at even more Class I areas beyond the 10
listed above,'' including 29 other Class I areas in the US and one
International Park in Canada. They claim that neither South Carolina
nor EPA demonstrate, or can demonstrate, that these additional Class I
areas are projected to be below their respective URP glidepaths at the
end of this planning period. They additionally assert that the same
VISTAS modeling shows that many of these 30 areas are projected to be
above their unadjusted and adjusted glidepaths at the end of this
planning period. Finally, the Conservation Groups assert that ``South
Carolina and EPA cannot rely on glidepath adjustments for these Class I
areas to claim that they will be below their glidepaths in 2028, as the
methods for glidepath adjustments on which South Carolina and EPA
potentially rely did not meet the requirements of the RHR.''
In conclusion, the Conservation Groups claim that South Carolina
and EPA ``do not and cannot show that all Class I areas affected by
South Carolina pollution will be below their respective URP glidepaths
at the end of the planning period, EPA's proposal to approve the 2022
SIP Revision based on its new URP policy is arbitrary, capricious, and
contrary to the law.''
Response 5.c: EPA disagrees with these comments. The RHR requires
states to submit a LTS that addresses regional haze visibility
impairment for each mandatory Class I area within the State and for
each mandatory Class I area located outside the State that may be
affected by emissions from the State.\21\ However, while the statute
says ``for a State the emissions from which may reasonably be
anticipated to cause or contribute to any impairment of visibility in
any such area,'' \22\ there is no specific statutory or regulatory
requirement to identify the precise set of Class I areas that may be
affected by emissions from the state, and there is no requirement to
establish a source contribution threshold in identifying those areas.
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\21\ See 40 CFR 51.308(f)(2).
\22\ See CAA section 169A(b)(2).
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The Conservation Groups also reference additional Class I areas
that they claim are potentially affected by emissions from South
Carolina and may potentially be above the 2028 URP for those areas. EPA
does not agree that emissions from South Carolina cause or contribute
to visibility impairment at all of those areas or that any or all of
those areas are above the 2028 URP.\23\ The VISTAS modeling results
cited by the Conservation Groups do not support the claim that all of
those additional areas
[[Page 57650]]
``may be affected'' by emissions from South Carolina (or that emissions
from South Carolina are ``reasonably anticipated to cause or contribute
any impairment in those areas''). While EPA has not identified a
numerical ``cause or contribute'' threshold, EPA does not agree, in
this instance, that any non-zero contribution can or should be
considered to ``cause or contribute'' to visibility impairment to an
out-of-state Class I area. Thus, states should merely reasonably
document contributions from emissions in their state to out-of-state
Class I areas and ensure that they meet the regulatory requirements,
which South Carolina has done. As the Conservation Groups themselves
note, South Carolina did so here in Table 10-3 and Figure 10-1 of its
submittal, which contains highlights of even more detailed information
contained in Appendix E-7.
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\23\ The RPGs for the areas identified by the Conservation
Groups are below the adjusted 2028 URP. See Haze Plan Appendix F-3.
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EPA similarly disagrees with the Conservation Groups' claims about
VISTAS' modeling. Detailed responses to the modeling comments discussed
above and other related comments regarding the VISTAS modeling can be
found in Responses 6.a, 7, and 8 below.
Comment 6: The Conservation Groups contend that EPA's proposal to
approve South Carolina's reliance on the VISTAS' visibility modeling is
arbitrary, capricious, and contrary to law because the Agency ignored
significant flaws in this modeling. They state that they informed
VISTAS and EPA of significant errors in the visibility modeling through
a 2021 letter and that EPA did not acknowledge these errors in the
NPRM. They contend these errors affected the source selection process
for all of the VISTAS states. Consequently, they assert that South
Carolina improperly excluded major sources of haze-forming pollution
from FFAs. These alleged errors are addressed in Comments 6.a through
6.c below.
Comment 6.a: The Conservation Groups contend that the VISTAS
modeling significantly underpredicted the contribution of sulfates to
visibility impairment at Class I areas on the 20 percent most impaired
days and that this underprediction was largest during the summer months
when sulfate extinction is known to be a major contributor to
visibility impairment, and when visibility impairment is most
problematic. They also assert that these errors resulted in the
modeling not meeting VISTAS' model performance goals and modeling
acceptance criteria for a number of Class I areas. They provide
examples of specific Class I areas in and around South Carolina where
they contend the visibility modeling exceeded the acceptance criteria
for sulfate at Great Smoky Mountains National Park (Great Smoky
Mountains) by -6.92 percent and at Okefenokee by -11.42 percent and
that at Cape Romain the modeling ``barely satisfies'' the less than
plus or minus 30 percent criteria at -28.85 percent. They further
assert that, although the State claims it corrected for these
underpredictions through the use of relative response factors (RRFs)
for its 2028 future year projections, neither South Carolina nor EPA
assessed whether use of RRFs adequately corrected for errors in the
modeling. They state that according to EPA's 2018 Modeling Guidance,
the effectiveness of RRFs is dependent on the type of data used to
calculate them.\24\
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\24\ EPA's Modeling Guidance for Demonstrating Air Quality Goals
for Ozone, PM2.5 and Regional Haze (November 29, 2018) (``2018
Modeling Guidance'') is in the docket for this rulemaking and is
also available at: <a href="https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf">https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf</a>.
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Response 6.a: EPA disagrees that there are significant flaws in
South Carolina's 2028 visibility modeling that resulted in excluding
major sources of haze-forming pollution from evaluation via FFAs for
the second planning period. As the Conservation Groups state, South
Carolina relied upon the photochemical visibility modeling performed by
VISTAS to project the impact of the State's 2028 SO<INF>2</INF> and
NO<INF>X</INF> emissions on visibility in both in-state and out-of-
state Class I areas. VISTAS performed the modeling in accordance with
the principles described within EPA's 2018 Modeling Guidance.\25\ In
2018, EPA approved the Quality Assurance Project Plan \26\ prepared by
VISTAS for performing the modeling and reviewed and provided comments
on the VISTAS Modeling Protocol. EPA also reviewed the VISTAS final
modeling reports and data relied upon by South Carolina and found them
acceptable.
---------------------------------------------------------------------------
\25\ Id.
\26\ The April 3, 2018, Quality Assurance Project Plan for the
VISTAS II Regional Haze Project is located in Appendix A-1 of the
Haze Plan.
---------------------------------------------------------------------------
Regarding sulfate predictions, Figure 6-7 of South Carolina's Haze
Plan shows the results of the normalized mean bias and normalized mean
error statistical model performance tests for sulfates across the
VISTAS region. Figure 6-7 does show that the modeled sulfate levels are
biased low, with some values falling outside of the model performance
criteria. However, as discussed below, these biases are not uncommon in
photochemical modeling analyses and can be addressed with additional
analyses. As noted by the Conservation Groups, the normalized mean bias
(NMB) statistic on the 20 percent most impaired days for Cape Romain in
South Carolina shows model underprediction, but it is within the VISTAS
performance criteria. Figure 6-27 in South Carolina's Haze Plan
graphically shows that the VISTAS Criteria for NMB (less than plus or
minus 30 percent) and Normalized Mean Error (NME) (less than plus or
minus 50 percent) are met for the Cape Romain Class I area in South
Carolina.
Model bias and error, either high or low, is not uncommon in
photochemical modeling analyses due to uncertainties in model inputs
and the scientific model formulation, and the fact that all air quality
models are simplified approximations of the complex phenomena of
atmospheric chemistry, fate, and transport of pollutants. Section 6.0
of EPA's 2018 Modeling Guidance discusses uncertainties that may affect
model results and provides recommendations to mitigate modeling bias
and uncertainty. South Carolina acknowledges that model performance
generally underpredicted observed concentrations on the 20 percent most
impaired days but stated that model performance was assessed at the
``one atmosphere'' level and was deemed acceptable for its regulatory
determinations in the Haze Plan (which references the 2018 Modeling
Guidance in several instances). The 2018 Modeling Guidance states that
it is not appropriate to use a ``bright-line test'' for distinguishing
between adequate and inadequate photochemical model performance for a
single performance test statistic.\27\ EPA's 2018 Modeling Guidance
instead recommends using a ``weight of evidence'' approach for
evaluating model performance holistically.\28\
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\27\ See 2018 Modeling Guidance at 69 (``Further, even with a
single performance test, it is not appropriate to assign ``bright
line'' criteria that distinguish between adequate and inadequate
model performance.'').
\28\ Id. (``[T]he EPA recommends that a ``weight of evidence''
approach be used to determine whether a particular modeling
application is valid for assessing the future attainment status of
an area.'').
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As discussed in Section 5.2(d) of EPA's ``Guideline on Air Quality
Models'' contained in 40 CFR part 51, Appendix W, there are no specific
levels of any model performance metric that indicate acceptable model
performance. The decision regarding acceptability is heavily influenced
by professional judgment of the reviewing authority, which is EPA in
this case. Based upon the overall performance of the model for all
pollutants affecting visibility, considered holistically, South
Carolina's conclusions that the modeling is
[[Page 57651]]
acceptable for use in the regional haze SIP analyses are reasonable,
and South Carolina provided a reasonable explanation for the model
bias.
Just as importantly, South Carolina took appropriate steps to
correct for this model bias. The Haze Plan explains that the model is
applied in a relative sense through the calculation of RRFs following
the procedures in 2018 Modeling Guidance for calculating 2028 future
year visibility impacts, which mitigates concerns about the low bias in
the sulfate model predictions. As described in EPA's 2018 Modeling
Guidance, RRFs are ``the fractional change in air quality
concentrations that is simulated due to emissions changes between a
base and a future year emissions scenario.'' \29\
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\29\ Id. at 103.
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Applying the model in a relative sense using the RRFs is an
important tool in mitigating the impacts of the sulfate modeling
underpredictions in the 2011 baseline year on the model projections for
the 2028 future year. Section 4.1 of the 2018 Modeling Guidance
provides a detailed explanation of why EPA recommends photochemical
modeling be applied in a relative sense and explains that problems
posed by model bias are expected to be reduced when using the relative
approach. Section 7.2.6.1 of South Carolina's Haze Plan explains the
calculation of 2028 visibility estimates using the RRF approaches
contained in EPA's 2018 Modeling Guidance. Using the RRF approach with
an average of five years of IMPROVE \30\ data on the 20 percent most
impaired days and 20 percent clearest days along with the relative
percent modeled change in all the PM species between 2011 and 2028
reduces the influence of the bias in sulfate-modeled (and other PM
species) values in the 2011 baseline year. The 2028 visibility
impairment projection is derived primarily from the five-year average
of actual IMPROVE monitoring data in 2009-2013 that was then scaled in
a relative sense by the modeling results. If the model were being
applied in an absolute sense, the low bias in the sulfate modeled
values would have a larger impact on the 2028 visibility projections.
For these reasons, South Carolina's use of the VISTAS model results to
inform source selection was reasonable due to the use of RRFs to
minimize the impacts of model bias. Additionally, regardless of the
sulfate model performance, a specific source selection approach is not
required by the RHR. South Carolina reasonably selected the nine
facilities (five of which are in-state) that have the highest impact on
visibility at the State's Class I area, as well as out-of-state Class I
areas, for emissions control analysis (see Response 7.a) and considered
the four statutory factors. EPA finds that South Carolina's source
selection methodology is consistent with the RHR because it was
reasonable and resulted in the selection of a reasonable set of sources
contributing to visibility impairment at Class I areas affected by
South Carolina's sources.
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\30\ IMPROVE visibility monitoring data is available at: <a href="https://vista.cira.colostate.edu/Improve/">https://vista.cira.colostate.edu/Improve/</a>.
---------------------------------------------------------------------------
Comment 6.b: The Conservation Groups state that VISTAS relied on an
``outdated'' 2011 baseline year for its 2028 future year emissions
projections and assumed that electric generating units (EGUs) would
operate in the exact same manner in 2028 as they did in 2011. Thus,
they assert that the model assumptions and results are incorrect
because EGUs are likely to have different load utilization in 2028 than
in 2011.
Response 6.b: South Carolina's use of a 2011 base emissions
inventory year to project emissions out to 2028 (the end of the second
planning period) is reasonable in this instance. Although it is always
preferable to use the most recent information available for modeling,
the 2011 baseline year inventory used by VISTAS was the latest region-
wide inventory available at the time that South Carolina's SIP
submittal was being developed during the VISTAS technical work, which
took place from December 2017 to February 26, 2021.\31\ In EPA's
experience, coordination among states such as those in the VISTAS
region takes time, and the modeling involved is time-consuming, highly
technical, and resource intensive. The modeling generally requires
hundreds of hours of time to gather the model input data (e.g.,
emissions, meteorology, land-use, etc.), prepare modeling protocols,
perform the modeling, and analyze the results. The computational
resources to run photochemical models are also very large.
``Mainframe'' clusters of a large number of computer processors are
required to run the models, and even using these powerful computers, it
takes weeks of computer run-time for a full-year model simulation.
Additionally, EPA's newer 2016-based modeling platform only became
available in September 2019,\32\ after VISTAS had already invested a
considerable amount of time and money into the regional haze modeling
analysis, including the Comprehensive Air Quality Model with Extensions
(CAMx) PSAT source apportionment modeling that was used to identify
sources to evaluate or reasonable progress. EPA develops the National
Emissions Inventory (NEI) suitable for use in such models every three
years.\33\ By design, the regional haze program requires states to
spend significant time in the planning phase, and this generally
necessitates the use of a baseline year that is substantially earlier
than the date the state submits its SIP to EPA.
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\31\ See ``Timeline'' for the VISTAS II Regional Haze Project
at: <a href="https://www.metro4-sesarm.org/content/vistas-regional-haze-project-intro">https://www.metro4-sesarm.org/content/vistas-regional-haze-project-intro</a>.
\32\ See ``Technical Support Document for EPA's Updated 2028
Regional Haze Modeling'' at: <a href="https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling">https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling</a>.
\33\ For more information on the NEI, see <a href="https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei">https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei</a>.
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In addition, there is no RHR requirement regarding the baseline
year for regional photochemical modeling (nor is photochemical modeling
required). At the time VISTAS began their regional haze modeling, EPA
did not have a more recent baseline emissions inventory year available
for state use in the second period regional haze plans. Furthermore,
South Carolina explains the use of this particular baseline year and
states that the 2011 emissions inventory was the most recently
available quality-assured statewide emissions inventory when the VISTAS
project began for the second planning period.\34\ Moreover, prior to
using this data, South Carolina discussed the selection of this
baseline year emissions inventory and received confirmation from EPA to
use this emissions inventory.\35\
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\34\ See Haze Plan at 22 (``The year 2011 was selected as the
modeling base year because the VISTAS 2028 emissions inventory is
based on the 2011 Version 6 EPA modeling platform. For the analyses
in this SIP, this period consists of those years surrounding 2011
(i.e. 2009-2013)''). See also Haze plan at 47 (``Calendar year 2011
satisfies the criteria in EPA's modeling guidance episode selection
discussion and is consistent with the base year modeling platform.
Specifically, EPA's guidance recommends choosing a time period which
reflects the variety of meteorological conditions that represent
visibility impairment on the 20 percent clearest and 20 percent
most-impaired days in the Class I areas being modeled (high and low
concentrations). This is best accomplished by modeling a full
calendar year. In addition, the 2011/2028 modeling platform was the
most recent available platform when VISTAS started their modeling
work. EPA's 2016-based platform became available at a later date
after VISTAS had already invested a considerable amount of time and
money into the modeling analysis. Using the 2016-based platform was
not feasible from a monetary perspective, nor could such work be
done in a timely manner.'').
\35\ See the January 29, 2018, email from EPA (Richard Wayland)
regarding use of a 2011 base year by VISTAS for regional haze in the
docket for this rulemaking.
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[[Page 57652]]
The 2011 emissions inventory was used to estimate emissions of
visibility impairing pollutants in 2028. VISTAS applied reductions
expected from federal and state regulations to the visibility impairing
pollutants NO<INF>X</INF>, PM, and SO<INF>2</INF>. South Carolina's
2028 emissions projections are based on the State's technical analysis
of the anticipated emission rates and level of activity for EGUs, other
point sources, non-point sources, on-road sources, and off-road sources
based on their emissions in the 2011 base year, considering growth and
additional emissions controls to be in place by 2028. In addition, the
VISTAS emissions inventory for 2028 accounts for post-2011 emission
reductions from promulgated federal, state, local, and site-specific
control programs.
Although South Carolina used 2011 as its emissions inventory base
year, as required by the RHR at 40 CFR 51.308(f)(2)(iii), South
Carolina also examined more recent emissions inventory information for
SO<INF>2</INF> and NO<INF>X</INF> for the years 2017, 2018, and 2019
and compared these emissions to the 2028 emission projections that were
used for modeling purposes in Section 7.6.5, Table 7-19 of its Haze
Plan. This helped to ensure that the State adequately considered more
recent emissions inventory information when developing LTS. The
technical information provided in the docket demonstrates that the
emissions inventory in the Haze Plan adequately reflects projected 2028
conditions. Given the aforementioned reasons, EPA finds the use of the
2011 baseline year by VISTAS (and thus South Carolina) reasonable.
Additionally, regardless of the use of a 2011 baseline year, a specific
source selection approach is not required by the RHR. South Carolina
reasonably selected the nine facilities (five of which are in-state)
that have the highest impact on visibility at the State's Class I area,
as well as out-of-state Class I areas, for emissions control analysis
(see Response 7.a) and considered the four statutory factors. EPA finds
that South Carolina's source selection methodology is consistent with
the RHR because it was reasonable and resulted in the selection of a
reasonable set of sources contributing to visibility impairment at
Class I areas affected by South Carolina's sources.
Comment 6.c: The Conservation Groups state that VISTAS used
``outdated'' monitoring data for its 2028 future year projections that
did not reflect an observed shift in nitrate contribution to visibility
impairment in the southeastern United States in the recent past. They
therefore contend that this resulted in the exclusion of major
NO<INF>X</INF> sources from the modeling results.
Response 6.c: Regarding the Conservation Groups' comment that the
2009-2013 modeling base period did not reflect more recent changes in
nitrate contributions, EPA discussed its views on this issue in detail
in the NPRM. Nitrates are also discussed in Response 8, below. EPA
agrees that after the 2009-2013 timeframe, nitrate impacts have become
more significant on some of the 20 percent most impaired days,
especially considering the significant decrease in SO<INF>2</INF>
emissions and measured sulfate concentrations as acknowledged in the
NPRM. EPA nonetheless agrees with South Carolina's conclusion that for
the second planning period, sulfates remain the dominant visibility-
impairing pollutant at the Class I areas affected by South Carolina and
that it is therefore reasonable for South Carolina to focus on
SO<INF>2</INF>-emitting sources during this period.
Comment 7: The Conservation Groups state that the purported errors
in the VISTAS modeling discussed in Comment 6 were carried forward into
the source selection process for VISTAS states, including South
Carolina, and that those errors caused VISTAS, and the states that
relied on the VISTAS process, to improperly exclude sources from FFAs.
In addition to the modeling errors, they state that South Carolina
adopted VISTAS' ``unreasonable'' source screening process that uses
Area of Influence (AoI) and PSAT analyses and applied unreasonably high
source selection thresholds. Based on these reasons, they conclude that
EPA's proposal to approve the State's source selection method is
arbitrary and capricious. The Conservation Groups' specific comments on
this topic are addressed in Comments 7.a through 7.h, below.
Comment 7.a: The Conservation Groups claim that South Carolina
employed unreasonably high source selection thresholds for the AoI
analysis, which were too restrictive and resulted in the identification
of only six South Carolina sources at the AoI step. Specifically, they
assert that by using percentage-based source selection thresholds, the
State's calculated threshold in absolute terms was higher for Class I
areas with the most severe visibility impairment, meaning that fewer
sources were identified at the AoI step for Class I areas with the
worst impairment. The Conservation Groups state that for the areas with
the worst visibility impairment, more sources should be selected to
make progress toward the natural visibility goal.
The Conservation Groups state that after performing the AoI
analysis and creating initial lists of facilities for PSAT tagging, the
VISTAS states then compared their lists and collaborated on the final
list of facilities for which AoI impacts were significant enough to
warrant further evaluation. They state that South Carolina failed to
provide any information on how the VISTAS states went through this
comparison process or any criteria used to determine whether an AoI
impact is significant enough. They contend that EPA and the State
therefore failed to adequately explain the AoI step in the selection
process.
Response 7.a: EPA disagrees with this comment. The RHR does not
require states to consider evaluating controls for all sources, all
source categories, or any or all sources in a particular source
category. Nor does the RHR expressly specify criteria for minimum
source selection thresholds.
These flexibilities are, however, not unbounded. The RHR requires
that ``[t]he State should consider evaluating major and minor
stationary sources or groups of sources, mobile sources, and area
sources. The State must include in its implementation plan a
description of the criteria it used to determine which sources or
groups of sources it evaluated and how the four factors were taken into
consideration in selecting the measures for inclusion in its long-term
strategy.'' \36\ In addition, the technical basis for source selection
must also be documented, as required by 40 CFR 51.308(f)(2)(iii). Thus,
states must utilize a reasonable source selection methodology, and
whatever choices states make regarding source selection should be
reasonably explained.\37\ South Carolina met these requirements.
Specifically, South Carolina discussed the criteria it used to
determine which sources or groups of sources were evaluated by the
State, including the use of AoI analysis, photochemical modeling (e.g.,
PSAT), and associated source selection thresholds for AoI and PSAT
tagging in its Haze Plan. South Carolina documented its use of these
approaches in extensive detail within Section 7.5 of the Haze Plan and
Appendix D-1 of the Haze Plan (relating to AoI analysis) and Section
7.6 and Appendices E-1a, E-1b, E-2a, E-2b, E-2c, E-2d, E-2e, E-2f, E-3,
E-4, E-5, E-
[[Page 57653]]
6, E-7a, and E-8 of the Haze Plan (relating to PSAT analysis).
---------------------------------------------------------------------------
\36\ See 40 CFR 51.308(f)(2)(i).
\37\ See 90 FR 36005, 36007.
---------------------------------------------------------------------------
South Carolina's documentation adequately demonstrates why its
source selection methodology--including the use of an AoI threshold
contribution of nitrate of three percent or more or sulfate of two
percent or more for in-state sources, and a threshold contribution of
four percent sulfate plus nitrate out-of-state sources for follow-up
PSAT tagging and a one percent PSAT threshold on a pollutant-by-
pollutant basis for source selection--is reasonable. For the reasons
stated herein and in the NPRM, EPA finds that South Carolina's source
selection methodology was reasonable and resulted in the selection of a
reasonable set of sources contributing to visibility impairment at
Class I areas affected by South Carolina's sources. The State's methods
for selecting sources for a control analysis and the State's AoI and
PSAT analyses identified sources in South Carolina having the highest
impact on visibility at Class I areas at the end of the second planning
period and identified sources outside of South Carolina having the
largest impacts on visibility at Cape Romain. A specific source
selection approach is not required by the RHR.\38\
---------------------------------------------------------------------------
\38\ Both of these approaches (AoI and PSAT) are example methods
in the 2019 Guidance. See subsection ``b) Estimating baseline
visibility impacts for source selection'' on pages 12-15 of the 2019
Guidance. PSAT is a type of photochemical modeling which is item 4
on page 13 of the 2019 Guidance. VISTAS' AoI analyses involve items
1-3 on page 13 of the 2019 Guidance.
---------------------------------------------------------------------------
The results of this methodology were reasonable as well. South
Carolina selected for emissions control analysis the nine sources with
the largest visibility impacts (accounting for both SO<INF>2</INF>/
sulfate and NO<INF>X</INF>/nitrate \39\) at Cape Romain and nearby
Class I areas in neighboring states. On the whole, SO<INF>2</INF>
emissions from the five in-state sources selected by South Carolina for
further analysis are projected to impact visibility at Class I areas as
described in Table 1, below.
---------------------------------------------------------------------------
\39\ South Carolina selected sources for PSAT modeling based on
the combined impact of sulfate plus nitrate. Sulfates and nitrates
were modeled together in the PSAT modeling with the other PM species
that impact visibility (e.g., direct PM, organic carbon, elemental
carbon, etc.). There were no sources with a sulfate impact below the
PSAT threshold(s), but a sulfate plus nitrate impact above the
threshold(s).
Table 1--Sulfate PSAT Contributions (Percent) for the Five Sources Selected for Further Analysis in Nearby Class
I Areas on the 20 Percent Most Impaired Days *
----------------------------------------------------------------------------------------------------------------
Wolf Island ***
Sources ** sulfate PSAT contributions to Class I areas Cape Romain (SC) Okefenokee (GA) (GA)
----------------------------------------------------------------------------------------------------------------
WestRock-Charleston.................................... 3.88 ................. .................
Century................................................ 2.43 ................. 1.30
Cross.................................................. 2.34 1.22 1.34
Winyah................................................. 1.39 ................. .................
IP-Georgetown.......................................... 1.71 ................. .................
----------------------------------------------------------------------------------------------------------------
* Note that fields with a ``-'' indicate that visibility impacts are below one percent.
** The Class I areas listed in Table 1, above, are included because the South Carolina facilities in this table
have a sulfate PSAT contribution of one percent or more at one or more of these areas.
*** Wolf Island has no IMPROVE monitor. Visibility at Wolf Island is assumed to be the same as the nearest Class
I area monitor located at Okefenokee.
Although these five sources are the largest contributors within
South Carolina to visibility impairment at Class I areas, most
anthropogenic impacts to visibility at Cape Romain come from outside of
South Carolina. This is illustrated in Figure 7-18 of the Haze Plan,
which provides the contributions from 2028 SO<INF>2</INF> and
NO<INF>X</INF> emissions to visibility impairment from all source
sectors for the 20 percent most impaired days in units of inverse
megameters (Mm<SUP>-1</SUP>). The entries in Table 2, below, show the
contributions from South Carolina, all other VISTAS states, and other
Regional Planning Organizations (RPOs) to Cape Romain.
Table 2--Contributions of 2028 SO2 and NOX Emissions From All Source Sectors to Visibility Impairment for the 20 Percent Most Impaired Days for Cape
Romain (Mm-\1\) *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Projected 2028
impairment on 20% All other CENRAP region LADCO region MANE-VU region All other
Class I area most impaired days SC VISTAS states *** *** *** regions ***
**
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cape Romain........................ 52.82 4.20 6.46 1.87 3.74 1.57 2.36
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Reference ``ATTACHMENT_A_PSAT_TAG_RESULTS_adjusted_09-02-2020.xls'' included in the docket. The columns to the right of ``Projected 2028 Impairment on
20% Most Impaired Days'' do not add up to the values in the ``Projected 2028 Impairment on 20% Most Impaired Days'' column due to international
emissions and boundary emissions visibility impacts not shown in this table.
** Value represents visibility impairment from all anthropogenic and natural sources.
*** ``CENRAP'' refers to Central Regional Air Planning Association (which is associated with the Central States Air Resource Agencies (CENSARA));
``LADCO'' refers to Lake Michigan Air Directors Consortium; MANE-VU; See also <a href="https://www.epa.gov/visibility/visibility-regional-planning-organizations">https://www.epa.gov/visibility/visibility-regional-planning-organizations</a> organizations.
Table 2 illustrates that South Carolina's in-state SO<INF>2</INF>
and NO<INF>X</INF> emissions account for a relatively small percentage
(eight percent) of total visibility impairment at Cape Romain impacted
by South Carolina sources.\40\
---------------------------------------------------------------------------
\40\ These percentages were calculated by dividing the ``SC''
column by the ``Projected 2028 20% Most Impaired Days Column'' and
multiplying by 100.
---------------------------------------------------------------------------
Likewise, the PSAT Tag Results spreadsheet referenced in Section
6.3 of Appendix E-7a of the Haze Plan shows the visibility impacts on a
facility-by-facility basis due to SO<INF>2</INF> emissions.
Specifically, the spreadsheet referenced in Attachment A of Appendix E-
7a shows the following SO<INF>2</INF> visibility
[[Page 57654]]
impacts to Class I areas impacted by South Carolina sources on the 20
percent most impaired days in units of Mm<SUP>-1</SUP>.
Table 3--2028 SO2 Visibility Impacts to Cape Romain on the 20 Percent
Most Impaired Days (Mm-\1\)
------------------------------------------------------------------------
Source Cape Romain
------------------------------------------------------------------------
WestRock-Charleston.................................. 0.523
Century.............................................. 0.327
Cross................................................ 0.316
Winyah............................................... 0.187
IP-Georgetown........................................ 0.230
------------------
Total of South Carolina Selected Sources......... 1.583
South Carolina Total Contribution............ 3.252
All Sources (including out-of-state 15.464
contribution)...........................
------------------------------------------------------------------------
The above data in Table 3 further supports that South Carolina's
source selection thresholds and source selection methodology were
reasonable. Specifically, on the 20 percent most impaired days, South
Carolina's in-state sources selected for further analysis are
responsible for approximately 48.68 percent of South Carolina's total
in-state SO<INF>2</INF> visibility impairment at Cape Romain.\41\
States are not required by the RHR to select every source in the state,
and South Carolina selected the in-state sources with the largest
visibility impacts on in-state and nearby Class I areas.
---------------------------------------------------------------------------
\41\ These percentages were calculated by dividing the ``Total
of Selected South Carolina Sources'' row in Table 3 by the ``South
Carolina Total Contribution'' row and multiplying by 100.
---------------------------------------------------------------------------
Table 3 also shows that most emissions of visibility-impairing
sulfates that impact South Carolina's Class I area on the 20 percent
most impaired days are emitted from outside of South Carolina. The same
general pattern holds for the 20 percent least impaired days as well.
South Carolina does not have jurisdiction through its SIP to regulate
sources outside of state boundaries. South Carolina did, however,
request FFAs from other states for an additional four facilities
outside of South Carolina through the interstate consultation
process.\42\ The ``regional'' nature of the regional haze program
necessarily requires South Carolina to rely on reasonable progress made
by other states, just as other states must rely on South Carolina to
make reasonable progress.
---------------------------------------------------------------------------
\42\ See Haze Plan at Section 7.6.
---------------------------------------------------------------------------
Turning to the Conservation Groups' other source selection
comments, they assert that by using a percentage threshold for AoI, the
calculated threshold in absolute visibility impact terms was higher for
Class I areas with the most severe visibility impairment, which
resulted in fewer sources being evaluated for reasonable progress for
the most visibility-impaired Class I areas. Thus, the Conservation
Groups assert that the use of a percentage threshold was unreasonable.
EPA disagrees with this comment. As noted above, states have
flexibility to adopt any source selection methodology so long as the
methodology is reasonable, and their choices are reasonably explained.
A percentage threshold, rather than one using an absolute visibility
threshold (Mm<SUP>-1</SUP> or dv), allowed South Carolina--like every
other VISTAS state--to select sources with the largest visibility
contributions to each Class I area regardless of the magnitude of
visibility impairment at a Class I area. This approach is reasonable.
Use of a percentage-based threshold produced a relative ranking of
visibility impairment to allow the State to focus on the sources
contributing to the largest amount of visibility impact at each
individual Class I area. Therefore, EPA finds that South Carolina's
source selection method is reasonable and adequately explained for the
reasons discussed above and within our proposal.
In addition, EPA disagrees with the Conservation Groups' assertion
that EPA and South Carolina failed to adequately explain the AoI step
of the source selection process. The AoI and PSAT tagging steps were
described in sections 7.5 and 7.6 of the Haze Plan, and EPA evaluated
the process in the NPRM. The two-step process of screening with the AoI
analysis and then applying the more refined PSAT source apportionment
modeling to sources that met the initial AoI screening criteria is a
sound technical approach for identifying sources to evaluate for
reasonable progress. Elements of South Carolina's AoI approach are
discussed in EPA's 2019 Guidance as a viable method to assess sources'
visibility impacts to Class I areas.\43\ South Carolina, along with
many of the VISTAS states, also relied upon the AoI initial screening
approach in its first planning period Haze Plan. VISTAS used the AoI
analysis as an initial screening step because it is a much simpler and
less resource intensive approach than using PSAT tagging to model
hundreds to thousands of potential sources. The AoI screening approach
identified a smaller subset of sources that could undergo refined
analysis using PSAT modeling. EPA finds the two-step process of first
screening with the AoI analysis followed by use of the more refined
PSAT source apportionment modeling to sources is valid, reasonable, and
adequately explained. Regarding the assertion that South Carolina
failed to provide any information on how the VISTAS states went through
its comparison process, this comment is not germane to South Carolina's
selection of sources for PSAT analysis because all of the facilities
above the State's AoI thresholds were selected for PSAT analysis. As
discussed above, EPA finds South Carolina's source selection method
reasonable and adequately explained.
---------------------------------------------------------------------------
\43\ EPA's 2019 Guidance at 12-14 discussing Q/d (emissions (Q)
divided by distance to a Class I area (d)), trajectory analyses,
residence time analyses, and source apportionment photochemical
modeling (e.g., CAMx PSAT).
---------------------------------------------------------------------------
Comment 7.b: The Conservation Groups state that VISTAS considered
sulfate and nitrate separately in the PSAT model analyses, which the
Conservation Groups allege does not align with how these pollutants act
in combination in the atmosphere along with other haze precursors, to
contribute to light extinction and visibility impairment. As a result,
they argue that VISTAS likely underestimated the overall visibility
impact of individual sources in its PSAT analysis.
Response 7.b: EPA disagrees with Conservation Groups' assertion
that VISTAS' separate consideration of sulfate and nitrate undermines
its
[[Page 57655]]
analysis of visibility impacts. Sulfates and nitrates were modeled
together in the PSAT modeling with the other PM species that impact
visibility (e.g., direct PM, organic carbon, elemental carbon, etc.).
Section 7.6.2 of the Haze Plan summarizes the results of the PSAT
modeling. This section states: ``[t]he adjusted PSAT results were used
to calculate the percent contribution of each tagged facility to the
total sulfate and nitrate point source (EGU + non-EGU) contribution at
each Class I area.'' Table 7-11 of the Haze Plan contains the specific
PSAT results for Cape Romain. South Carolina considered the PSAT
modeled results for sulfate and nitrate separately only to compare
against its selected one percent PSAT threshold for each of these
pollutants to identify a reasonable number of sources for further
analyses. The State's approach is reasonable for the reasons discussed
above, and it was adequately justified in the Haze Plan and in EPA's
NPRM.
Comment 7.c: The Conservation Groups state that VISTAS used an
outdated 2028 emissions projection to ``tag'' sources. They note that
although VISTAS documented that the initial 2028 emission inventory
projections were updated for the final modeling, the associated PSAT
modeling did not use the final 2028 inventory. The Conservation Groups
state that VISTAS scaled predicted sulfate and nitrate to the
corresponding changes in SO<INF>2</INF> and NO<INF>X</INF> emissions in
the updated 2028 inventory using a linear relationship between sulfate
and nitrate concentrations. They argue ample evidence shows that there
is a non-linear relationship between emissions and sulfate/nitrate
concentrations, and that this resulted in additional errors into the
modeling.
Response 7.c: EPA disagrees with this comment. VISTAS used the
original 2028 emissions inventory to perform the PSAT modeling, and the
original PSAT results were linearly scaled to reflect the updated 2028
emissions. Although linear scaling introduces some uncertainty to the
final PSAT results, EPA agrees with VISTAS and South Carolina that
adjusting the results to account for VISTAS' updated 2028 emissions
inventory using linear scaling is a reasonable approach to account for
VISTAS' updated 2028 emissions projections and is a better approach
than relying on the original PSAT modeling.
Linear scaling of photochemical modeling results to account for
changes in emissions is, in most cases, reasonable and is an accepted
practice by EPA. For example, EPA guidance recommends using EPA's
Modeled Emission Rates for Precursors (MERPs) for evaluating the
impacts of secondary particulate matter of 2.5 micrometers or less in
diameter (PM<INF>2.5</INF>) in Prevention of Significant Deterioration
(PSD) modeling analyses and allows for and recommends scaling of
photochemical modeling results based on emissions.\44\ This guidance
recommends an approach where the PM<INF>2.5</INF> impacts are estimated
using an archived national-scale photochemical modeling analysis,
performed using CAMx and Community Multiscale Air Quality (CMAQ) \45\
photochemical models, that uses hypothetical emissions sources, and
then linearly scaling the photochemical modeling results using the
ratio of the PSD project-specific source emissions to the modeled
emissions from the hypothetical source (see Equation 1 on page 3 of the
referenced April 30, 2024, MERPs memorandum). This approach is widely
used and accepted by state air quality agencies and EPA to account for
secondarily formed PM<INF>2.5</INF> from precursor emissions
(SO<INF>2</INF> and NO<INF>X</INF>) for PSD modeling analyses. Since
the regional haze modeling uses linear scaling with CAMx and for the
same PM<INF>2.5</INF> precursors (SO<INF>2</INF> and NO<INF>X</INF>) as
the MERPs analyses, EPA finds the method of linear scaling of PM
precursor emissions conducted by VISTAS to be an acceptable practice.
---------------------------------------------------------------------------
\44\ See ``Clarification on the Development of Modeled Emission
Rates for Precursors (MERPs) as a Tier 1 Demonstration Tool for
Ozone and PM<INF>2.5</INF> under the PSD Permitting Program,'' April
30, 2024, Memorandum from Tyler Fox to Regional Office Modeling
Contacts is available at: <a href="https://www.epa.gov/sites/default/files/2020-09/documents/epa-454_r-19-003.pdf">https://www.epa.gov/sites/default/files/2020-09/documents/epa-454_r-19-003.pdf</a>.
\45\ See <a href="https://www.epa.gov/cmaq">https://www.epa.gov/cmaq</a> for further information on
CMAQ.
---------------------------------------------------------------------------
Comment 7.d: The Conservation Groups note that South Carolina
relied on the PSAT modeling results for its multiple in-state sources
that are located less than 50 kilometers (km) from Cape Romain and
claim that PSAT modeling has been shown to be unreliable for sources
that are within a short distance from a Class I area,\46\ referencing
Federal Land Manager (FLM) \47\ guidance that addresses regional grid
models. According to the Conservation Groups, this guidance shows that
regional grid models are not preferred for sources located close to
Class I areas and that the grid size used by VISTAS is too small to
produce accurate results for those sources.
---------------------------------------------------------------------------
\46\ Citing to 2021 Gebhart North Carolina Report at 4.
\47\ EPA's regulations define ``Federal Land Manager'' as ``the
Secretary of the department with authority over the Federal Class I
area (or the Secretary's designee) or, with respect to Roosevelt-
Campobello International Park, the Chairman of the Roosevelt-
Campobello International Park Commission.'' See 40 CFR 51.301. The
U.S. National Park Service (NPS), U.S. Fish and Wildlife Service
(FWS), and U.S. Forest Service (USFS) are collectively referred to
as the ``Federal Land Managers'' or ``FLMs'' throughout this notice.
---------------------------------------------------------------------------
Response 7.d: The Conservation Groups state that PSAT modeling has
been shown to be unreliable for sources located less than 50 km from a
Class I area. However, they do not provide any specific model
performance information demonstrating that the CAMx model nor the PSAT
source apportionment tool have poor model performance for evaluating
visibility impacts from sources located within 50 km of any of the
Class I areas located in South Carolina.
Instead, the Conservation Groups provide qualitative arguments to
support their assertion. They assert that the FLMs' Air Quality Related
Values Work Group (FLAG) Guidance indicates that photochemical grid
models are not the preferred model for evaluating visibility impacts
from sources less than 50 km from Class I areas and reference the use
of direct plume impact models. However, they are inappropriately citing
the FLAG guidance and recommendations, which is not intended to apply
to photochemical grid modeling or outside of the permitting context.
The FLAG reference to direct plume models (e.g., Plume Visibility
Model) is only for evaluating visibility impacts under the New Source
Review (NSR)/PSD (NSR/PSD) permitting regulations and is not applicable
to regional haze analyses. EPA's regional haze regulations and guidance
do not require evaluations of direct plume impacts separate from the
photochemical modeling analyses used for regional haze visibility
analyses. Therefore, the argument is not relevant for the visibility
analyses for regional haze.
The Conservation Groups separately contend that South Carolina's
correlation analysis of the sulfate AoI versus PSAT presented in
Section 7.6.3 of the Haze Plan is flawed. They point out the scatter in
the AoI/PSAT ratio data for distances less than 100 km in Figure 7-29
of the Haze Plan and argue this makes the State's correlation
conclusions invalid. They also refer to the scatter in the sulfate
fractional bias values in Figure 7-30 in the Haze Plan and argue the
AoI versus PSAT correlation is invalid. EPA disagrees. While there is
more scatter between the data points less than 100 km from the Class I
area, there is clearly a trend that the AoI values are much larger than
the PSAT values within 100 km compared to the ratios for further
distances. There is logic to this result due to the way the
[[Page 57656]]
AoI metric is calculated using the Extinction Weighted Residence Times
(EWRT) multiplied by the Emissions (Q) divided Distance (d) (EWRTxQ/d).
The EWRT is calculated using the frequency that winds (represented by
Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back
trajectories) pass over a specific geographic area (represented by a
modeling grid cell) on the path to the Class I area.\48\ For sources
located less than 100 km from a Class I area, there is likely to be a
higher frequency of the HYSPLIT back trajectories passing over the 12
km grid cell containing the source, thus the EWRT and AoI value will be
larger. The CAMx PSAT modeling is a more refined photochemical modeling
approach that calculates the atmospheric fate and transport of the PM
precursors and their chemical reactions to form visibility impairing
pollutants (e.g., ammonium sulfate). Therefore, compared to the AoI
screening process, the refined PSAT technique is less likely to
overestimate the visibility impacts for sources located within 100 km
of the Class I area. Regarding the scatter of the data resulting in the
AoI to PSAT fractional bias correlation, EPA acknowledges that there is
scatter in the data which is reflected in the 0.72 coefficient of
determination (R\2\) value shown in Figure 7-30 in the Haze Plan.
However, this level of correlation is not uncommon in these types of
modeling data analyses, and the results are reasonable. For these
reasons, South Carolina's correlation approach is valid.
---------------------------------------------------------------------------
\48\ See Section 7.5 of the Haze Plan for additional detail.
---------------------------------------------------------------------------
The photochemical modeling employed by VISTAS and South Carolina is
the most refined methodology available for evaluating regional haze
visibility impacts. Moreover, South Carolina's AoI screening process
identified sources located within 50 km of its Class I areas, including
the WestRock-Charleston and Century facilities located 29 km and 39 km,
respectively, from Cape Romain that met the PSAT source selection
criteria and further underwent reasonable progress analysis. As
discussed above, South Carolina demonstrated in Section 7.6.3 of the
Haze Plan that the AoI screening technique tends to overestimate
visibility impacts for sources located within 100 km of a Class I area.
Based upon this AoI overestimation, in Section 7.6.4 of the Haze Plan,
South Carolina explains why some sources located less than 100 km from
its Class I areas were not tagged for PSAT modeling and thus were not
selected for FFAs. South Carolina's justification regarding why the
other sources within 100 km were not selected for FFAs is reasonable.
Comment 7.e: The Conservation Groups claim that South Carolina's
use of a percent-based threshold at the PSAT step biased the process
against heavily polluted Class I areas. They explain that reliance on
the percent-based threshold would require source impacts to be 80 times
larger for the most visually impaired Class I areas versus the least
visually impaired Class I areas to be selected.
Response 7.e: EPA disagrees with this comment. Section 7.6.4 of the
Haze Plan explains the State's rationale for using a one percent PSAT
threshold to select sources for a reasonable progress evaluation. Using
a percentage-based threshold enabled the State to identify the sources
that contribute most to visibility impairment at the Class I areas,
regardless of the magnitude of visibility impairment at each Class I
area. Therefore, South Carolina's targeting of sources with the largest
visibility contributions to each Class I area regardless of magnitude
of visibility impairment at a Class I area is reasonable. Use of a
percentage-based threshold produced a relative ranking of impacts on
visibility impairment, allowing the State to focus on the sources with
the greatest visibility impacts on each individual Class I area.
Regardless of whether a relative or absolute threshold was used, South
Carolina's source contribution threshold identified the largest sources
for evaluation of emissions measures. Therefore, the methodology is
reasonable and was adequately documented in its Haze Plan.
Comment 7.f: The Conservation Groups claim that neither South
Carolina nor EPA have provided adequate justification to support the
source selection thresholds, and therefore, the source selection
process is arbitrary and capricious. They state four ways in which
South Carolina's justification misses the mark. First, they argue that
South Carolina did not provide an explanation for why it set a
different selection threshold for out-of-state sources, or with regard
to that threshold, include a description of the criteria used to
determine which sources or groups of sources it evaluated in violation
of 40 CFR 51.308(f)(2)(i). Second, they argue that South Carolina
effectively claims that the URP is a safe harbor in violation of the
CAA, RHR, and EPA interpretation, and the State did not need to select
additional sources because Cape Romain is projected to be below the URP
in 2028 without any additional controls. Third, the Conservation Groups
assert that South Carolina inappropriately claims that emission
reductions already achieved in the second planning period excuses the
State from selecting additional sources. Lastly, the Conservation
Groups maintain that South Carolina unreasonably set its selection
thresholds to only select the largest sources for further analysis,
pointing to EPA guidance. They note that the USFS explained that South
Carolina's source selection process found the sources selected by South
Carolina accounted for just 24 percent, 12 percent, 47 percent, and 38
percent of emissions that impact Linville Gorge National Wilderness
Area (Linville Gorge), Shining Rock National Wilderness Area (Shining
Rock), Joyce Kilmer-Slickrock (Joyce Kilmer), and Cohutta National
Wilderness Area (Cohutta), respectively.
Response 7.f: EPA disagrees with the Conservation Groups'
contention that South Carolina did not adequately justify its source
selection thresholds.
First, regarding the out-of-state AoI threshold, no out-of-state
sources exceeded South Carolina's in-state thresholds of two percent
sulfate or three percent nitrate at Cape Romain; therefore, the higher
out-of-state threshold had no impact on the outcome of the Haze Plan.
As discussed in Response 7.a, South Carolina's source selection method
is reasonable and adequately explained.
Second, EPA disagrees with the Conservation Groups' assertion that
South Carolina effectively claims that the URP is a safe harbor, and
the State did not need to select additional sources because Cape Romain
is projected to be below the URP in 2028 without any additional
controls. As discussed in Response 7.a, South Carolina did not claim
the URP to be a safe harbor. South Carolina based its source selection
on AoI and PSAT analyses, selected the sources with the largest
visibility impacts to Class I areas impacted by South Carolina, and
considered the four statutory factors.
Third, the comment that South Carolina ``claims that already
achieved emission reductions in the second planning period excuse it
from selecting additional sources'' is unclear. The Haze Plan contains
no such statement. As discussed in Response 7.a, South Carolina's
source selection methodology is reasonable and is adequately documented
in its Haze Plan. The fact that sources were not selected for FFAs for
either SO<INF>2</INF> or NO<INF>X</INF> for this planning period is the
result of the reasonable application of the State's source selection
process and source selection thresholds.
[[Page 57657]]
Finally, EPA disagrees with the Conservation Groups assertion that
South Carolina unreasonably set its selection thresholds to only select
the largest sources for further analysis. As discussed further in
Response 7.a, states have flexibility to adopt any source selection
methodology so long as the methodology is reasonable and their choices
are reasonably explained. A percentage threshold, rather than one using
an absolute visibility threshold (Mm-1 or dv), allowed South Carolina--
like every other VISTAS state--to select sources with the largest
visibility contributions to each Class I area regardless of the
magnitude of visibility impairment at a Class I area, which EPA agrees
is reasonable. Regarding the four Class I areas identified in Comment
7.f, no South Carolina facility exceeded the State's AoI source
selection thresholds.\49\ As discussed in Response 7.a, EPA evaluated
South Carolina's source selection process and determined it to be
reasonable; thus, the facilities the State selected for further
analysis were reasonable.
---------------------------------------------------------------------------
\49\ New-Indy Catawba Pulp and Paper Plant (New-Indy Plant) was
the South Carolina facility with the largest impact to Linville
Gorge (0.77 percent sulfate; 0.02 percent nitrate), Shining Rock
(0.46 percent sulfate; 0.03 percent nitrate), Joyce Kilmer (0.19
percent sulfate; 0.00 percent nitrate), and Cohutta (0.34 percent
sulfate; 0.04 percent nitrate).
---------------------------------------------------------------------------
Comment 7.g: The Conservation Groups contend that EPA did not
address ``significant flaws'' in the VISTAS modeling and source
selection process and that EPA improperly concluded that South
Carolina's selection of five in-state sources was reasonable because it
enabled the identification of sources with the largest visibility
impacts. They argue that this is contrary to EPA's guidance which
states that a source selection threshold that captures only a small
portion of a state's contribution to visibility impairment in Class I
areas is more likely to be unreasonable and contrary to the CAA which
does not authorize states or EPA to select only the largest
contributors to visibility impairment. They assert that South Carolina
should have used a different selection method with a lower threshold,
such as a Q/d with a threshold of five or lower, to capture the
meaningful portion of in-state sources.
Response 7.g: EPA disagrees with the assertion that South
Carolina's selection of the five in-state sources contributing to
visibility impairment at Class I areas is contrary to EPA's guidance.
The PSAT modeling performed by VISTAS found that the five sources
selected by South Carolina for further analysis have the largest
contribution to visibility impairment of any point sources in the
State. As discussed in Response 7.a, the PSAT modeling results show
that the total cumulative contribution to visibility impairment on the
20 percent most impaired days at South Carolina's Class I area from all
SO<INF>2</INF> and NO<INF>X</INF> emitting sources in the State is
relatively small, at about 8.0 percent for Cape Romain based on Table
2, above.\50\ Given state discretion in selecting sources to evaluate
for emissions controls, and since the SO<INF>2</INF> and NO<INF>X</INF>
emissions from all point sources in South Carolina contribute a
relatively small amount to the total visibility impairment at its Class
I area, the State's selection of the five largest in-state sources that
contribute to visibility impairment is reasonable.
---------------------------------------------------------------------------
\50\ See footnote 40.
---------------------------------------------------------------------------
Regarding the Conservation Groups' claim that the State should have
adopted a different selection method (such as Q/d) with a lower
threshold to select more sources in South Carolina, as discussed above,
a state is not required to evaluate all sources of emissions in each
planning period. Instead, a state may reasonably select a set of
sources for an analysis of control measures. Selecting a set of sources
for analysis of control measures in each planning period is also
consistent with the RHR, which sets up an iterative planning process
and anticipates that a state may not need to analyze control measures
for all sources in a given SIP revision. Moreover, use of Q/d (which
simply involves dividing the quantity of emissions by the distance to a
Class I area) does not consider transport direction/pathway, dispersion
and photochemical processes, or the particular days that have the most
anthropogenic impairment due to all sources. Therefore, compared to
photochemical modeling, using a simple Q/d technique, as the
Conservation Groups suggest, would have resulted in a less accurate
quantification of visibility impacts on Class I areas. As discussed in
detail above, South Carolina's reliance on VISTAS modeling and the
State's source selection methodology are well documented within the SIP
submittal and reasonable.
Comment 7.h: The Conservation Groups state that EPA asserts in its
proposal that South Carolina's source selection method is reasonable
because: (1) visibility conditions at in-state Class I areas are
projected to improve and have improved since the baseline period, (2)
EPA's evaluation of the 2015-2019 IMPROVE data on the 20 percent most
impaired days for Cape Romain confirmed that ammonium sulfate is the
dominant visibility impairing pollutant at this area during that time
period, and (3) ammonium nitrate contributions to regional haze at the
State's Class I area remain relatively low at eight percent of the
total visibility impairment as compared to ammonium sulfate at 56
percent. They argue, however, that projected visibility condition
improvement at South Carolina's Class I areas and the fact that those
areas are below their respective URPs are not a valid basis to approve
the State's flawed selection method. They state that despite EPA's URP
policy, the URP is not a safe harbor and that states cannot avoid
requiring sources to install reasonable controls merely because there
have been emissions reductions due to ongoing air pollution controls
since the first planning period or because visibility is projected to
improve at Class I areas. The Conservation Groups state that even if
Class I areas impacted by South Carolina sources are already on or
below the glidepath, the CAA and RHR still require the State to engage
in rigorous source selection and conduct FFAs to determine whether
additional control measures are reasonable.
Response 7.h: EPA agrees that the URP is not a ``safe harbor'' to
avoid evaluating and determining the emission reduction measures that
are necessary to make reasonable progress by considering the four
statutory factors. However, being below the URP is relevant to whether
a state needs to perform a ``robust demonstration'' based on the
requirements in 40 CFR 51.308(f)(3)(ii)(A) and 40 CFR
51.308(f)(3)(ii)(B).\51\ It is also relevant to EPA's application of
the URP Policy. EPA's responses addressing the URP Policy are contained
in Responses 1 through 5. EPA did not approve South Carolina's source
selection methodology based on projected visibility improvement at any
Class I area or the URP. See the NPRM and Response 7.a that projected
visibility condition improvement at South Carolina's Class I areas and
the fact that those areas are below their respective URPs. As discussed
in Response 7.a, South Carolina based its source selection on AoI and
PSAT analyses, not on the URP.
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\51\ Emissions from South Carolina are not reasonably
anticipated to contribute to visibility impairment in any Class I
areas that are above the 2028 URP, which is relevant to whether a
state needs to perform a ``robust demonstration'' based on the
requirements in 40 CFR 51.308(f)(3)(ii)(A) and 40 CFR
51.308(f)(3)(ii)(B).
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Comment 8: The Conservation Groups assert that EPA incorrectly
endorses South Carolina's decision to exclude consideration of
NO<INF>X</INF> controls in any
[[Page 57658]]
FFAs, and therefore, EPA ignores an important aspect of the problem.
They contend that VISTAS' modeling did not accurately reflect the shift
in the 20 percent most impaired days and the corresponding increase in
the contribution of nitrate to visibility impairment at Southeastern
Class I areas. They state that more of the 20 percent most impaired
days now occur in the winter, when nitrate plays a bigger role in
visibility impairment; that South Carolina explained in its SIP that
``nitrate concentrations are higher on winter days and are more
important for the coastal sites where the 20% most impaired days occur
during the winter months;'' and that Cape Romain is a coastal Class I
area.
The Conservation Groups claim that EPA, South Carolina, and the
USFS have noted that nitrate's contribution to visibility impairment
has increased in recent years. They contend that South Carolina's Haze
Plan confirms that nitrate contributes to a substantial portion of
light extinction at several Class I areas, and that on multiple of the
20 percent most impaired days, for impacted Class I areas during the
2015-2019 period, nitrate is the biggest contributer. Furthermore, they
note that more recent IMPROVE data at Great Smoky Mountains shows the
contribution of nitrate to light extension on the 20 percent most
impaired days have increased. They also note EPA's general expectation
that states will, at a minimum, consider both SO<INF>2</INF> and
NO<INF>X</INF> in this planning period, and they assert that there are
multiple sources of significant NO<INF>X</INF> emissions that South
Carolina should have analyzed for NO<INF>X</INF> controls.
Response 8: EPA disagrees with this comment. The RHR does not
prescribe which visibility impairing pollutants must be evaluated in
the FFAs. When selecting sources for analysis of control measures, a
state may focus on the PM species that dominate visibility impairment
at the Class I areas affected by emissions from the state and then
select only sources with emissions of those dominant pollutants and
their precursors. EPA has recommended that states that do not evaluate
SO<INF>2</INF> and NO<INF>X</INF> in both source selection and control
evaluations show why consideration of these pollutants would be
unreasonable, especially if the state considered both of these
pollutants in the first planning period.\52\
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\52\ South Carolina considered SO<INF>2</INF> for FFAs conducted
in the first planning period. See 82 FR 39079.
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South Carolina followed these recommended approaches here. South
Carolina considered both SO<INF>2</INF> emissions (via sulfates
visibility impacts) and NO<INF>X</INF> emissions (via nitrates
visibility impacts) in the source selection process. As part of the
Haze Plan, South Carolina presented the results of PSAT modeling
conducted by VISTAS to estimate the projected impact of statewide
SO<INF>2</INF> and NO<INF>X</INF> emissions across all emissions
sectors in 2028 on total light extinction for the 20 percent most
impaired days in all Class I areas in the VISTAS modeling domain. The
result of this process was that while sources were selected for
SO<INF>2</INF> control analysis determinations, no sources in South
Carolina met the State's nitrate source selection thresholds.
Therefore, South Carolina did not select any sources for a
NO<INF>X</INF> emissions control evaluation. Contrary to the
Conservation Groups' assertion that South Carolina made a ``decision''
not to consider NO<INF>X</INF> controls in any FFAs, it was South
Carolina's application of its source selection process, in combination
with data and modeling showing that SO<INF>2</INF> is the dominant
visibility impairing pollutant, that resulted in South Carolina only
selecting sources for SO<INF>2</INF> emissions control analyses and not
NO<INF>X</INF> emissions control analyses.
Additionally, to better understand the trends in PM species
contributions to visibility impairment, South Carolina examined more
recent IMPROVE monitoring data. More recent IMPROVE monitoring data
shows that ammonium sulfate remains the dominant visibility impairing
pollutant at Cape Romain and neighboring Class I areas as discussed in
Section 2.5.2 of the Haze Plan (particularly Figures 2-4 through 2-6
for the 2009-2013 period) and in Section 2.6.2 (particularly Figures 2-
7 through 2-9 for the 2014-2018 period). The 2015-2019 IMPROVE
monitoring data (the most recent data available at the time) from the
IMPROVE website identifies the relative contributions of PM species
contributing to the total visibility impairment at Cape Romain, which
is shown in Table 4, below. In spite of increased nitrate contributions
on the 20 percent most impaired days (as the Conservation Groups note,
often on winter days), as indicated in that table, ammonium nitrate
contributions to regional haze at Cape Romain remain relatively low at
around eight percent of the total visibility impairment as compared to
ammonium sulfate at 56 percent.
Table 4--2015-2019 Speciated IMPROVE Monitoring Data (Percent) for Cape Romain \53\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fine
Ammonium Ammonium Organic Elemental Fine soil Coarse sea
sulfate nitrate carbon carbon mass salt
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cape Romain..................................................... 56 8 19 5 1 7 3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Furthermore, in Table 7-14 of the Haze Plan, the State provided a
calculation of the sulfate and nitrate EWRT used in the AoI analysis
for Cape Romain for the 20 percent most impaired days, demonstrating
that the sulfate EWRT are significantly higher than the nitrate EWRT.
This further supports the importance of focusing on SO<INF>2</INF>
emissions reductions for this planning period. The State's rationale
for focusing on SO<INF>2</INF> controls in the FFAs is summarized in
South Carolina's SIP submittal and the NPRM.\54\
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\53\ See the spreadsheet containing the 2015-2019 speciated
IMPROVE monitoring data for South Carolina's Class I area included
in the docket for this rulemaking.
\54\ See Haze Plan, Section 2, particularly Figure 2-4, Section
7 (particularly Figures 7-14 through 7-18), and Section 10
(particularly Figures 10-1); 90 FR 36012.
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With respect to the Conservation Groups' assertion that nitrate is
the biggest contributor to light extinction on multiple of the 20
percent of most impaired days for Cape Romain during the 2015-2019
period (especially on winter days), as described above, the average
nitrate contribution across the 20 percent most impaired days is still
relatively small. Thus, while nitrate impairment may be relatively high
on a particular day, the data that states are required to use for
regional haze as specified in 40 CFR 51.301 and 40 CFR 51.308(f)(1)
show ammonium nitrate only contributed around eight percent the total
visibility impairment (during the 2015-2019 period). Regarding the
comment on the contribution of nitrates
[[Page 57659]]
to visibility impairment at Great Smoky Mountains, it is unclear why
the Conservation Groups are referencing nitrate impacts at this Class I
area in this rulemaking. Using the data available at the time, the
VISTAS PSAT modeling analyses projects that the cumulative nitrate
visibility impact at Great Smoky Mountains from all NO<INF>X</INF>
emissions sources in South Carolina is 0.4 percent (all South Carolina
sources modeled nitrate at Great Smoky Mountains (0.014
Mm<SUP>-1</SUP>) divided by total modeled nitrate impact at Great Smoky
Mountains (3.382 Mm<SUP>-1</SUP>) = 0.0041 x 100 = 0.4 percent)).\55\
Regardless, the NPS chart referenced by the Conservation Groups shows
that sulfates continue to be the dominant visibility impairing
pollutant at Great Smoky Mountains on the most impaired days.\56\
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\55\ See ``ATTACHMENT_A_PSAT_TAG_RESULTS_adjusted_09-02-
2020.xls'' spreadsheet included in the docket for this rulemaking.
\56\ See Exhibit 38 to the Conservation Groups' September 29,
2025, comment letter.
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For these reasons, South Carolina's justification for not
evaluating sources selected for SO<INF>2</INF> emission control
analyses for a separate NO<INF>X</INF> emission control analysis is
reasonable for this planning period. The trends in PM species'
contributions to visibility impairment will continue to be evaluated in
future planning periods. If the data warrants consideration of
NO<INF>X</INF> controls in future planning periods, EPA expects that
South Carolina will address potential NO<INF>X</INF> controls in future
regional haze SIP revisions.
Comment 9: The Conservation Groups assert that EPA ignores that
South Carolina unreasonably excluded significant sources from FFAs.
They state that to correct errors in the source selection method, EPA
must require South Carolina to assess additional sources identified by
NPS and NPCA [Williams Generating Station (Williams Station), Wateree
Generating Station (Wateree Station), Cope Generating Station (Cope
Station), Sylvamo Eastover Mill (Sylvamo Mill, formerly International
Paper--Eastover), Argos Harleyville Cement Plant (Argos Plant), Holcim
Holly Hill Plant (Holcim Plant), New-Indy Plant (formerly Resolute FP
US INC), WestRock Florence Paper Mill (WestRock-Florence)] which have
emissions that likely contribute to impairment in Class I area.
Furthermore, the Conservation Groups assert that EPA must find that the
State arbitrarily refused to consider cost-effective control upgrades
or measures improving efficiency of existing controls at these sources
and Winyah. Additionally, they claim that South Carolina's analysis
unlawfully relied on unenforceable, speculative emission reductions to
avoid conducting control analyses for several of those facilities, and
the State arbitrarily and unlawfully refused to conduct FFAs for
several EGUs that contribute to visibility impairment in Class I areas.
The comments regarding specific sources identified by the Conservation
Groups are addressed in Comments 9.a, 10, and 10.a-10.c, below.
Response 9: As explained in Response 7.a and in the NPRM, the RHR
does not require states to select and consider controls for all
sources, all source categories, or any or all sources in a particular
source category. Nor does the RHR expressly specify criteria for
minimum source selection thresholds. States have discretion to choose
reasonable source selection criteria, and sources that meet the state's
criteria are selected for an evaluation of potential control options
for specific visibility impairing pollutants by considering the four
statutory factors in CAA section 169A(g)(1).
South Carolina did not select Williams Station, Wateree Station,
Cope Station, Sylvamo Mill, Argos Plant, Holcim Plant, New-Indy Plant,
or WestRock-Florence for FFAs because these facilities did not exceed
the State's source selection thresholds. As discussed in Response 7.a,
South Carolina's source selection methodology is reasonable and is
adequately documented in its Haze Plan. Winyah exceeded the State's
source selection threshold for SO<INF>2</INF>, and as discussed in
Responses 10 and 10.a-10.c, below, EPA has determined that South
Carolina's effective controls demonstration for Winyah is reasonable.
As discussed in Response 8, NO<INF>X</INF> impacts were considered by
the State, but no sources were selected for a NO<INF>X</INF> control
evaluation because visibility impacts for NO<INF>X</INF> did not exceed
the State's source selection threshold. See Responses 7.a (source
selection), 8 (nitrates/NO<INF>X</INF> controls), and 10 (Winyah) for
further discussion.
Regarding the claim that South Carolina's analysis unlawfully
relied on unenforceable, speculative emission reductions to avoid
conducting control analyses for several of those facilities, EPA
disagrees that a SIP enforceable mechanism must be put in place for
those sources. Williams Station, Wateree Station, Cope Station, Sylvamo
Mill, Argos Plant, Holcim Plant, New-Indy Plant, and WestRock-Florence
were not selected for control evaluation because they did not exceed
the State's source selection thresholds, and therefore, no measures are
necessary at these facilities for reasonable progress. As discussed in
Response 7.a, South Carolina's source selection methodology is
reasonable and is adequately documented in its Haze Plan. The fact that
these sources were not selected for FFAs for either SO<INF>2</INF> or
NO<INF>X</INF> for this planning period is the result of the reasonable
application of the State's source selection process and source
selection thresholds. Although Winyah exceeded the State's source
selection threshold for SO<INF>2</INF>, EPA has determined that South
Carolina's effective controls demonstration for Winyah is reasonable.
See Response 10 for further discussion. South Carolina did not identify
any measures at Winyah as necessary for reasonable progress. Because no
measures are necessary for reasonable progress at these nine
facilities, the CAA and RHR do not require South Carolina to include
enforceable measures for these facilities in its LTS.
Comment 9.a: The Conservation Groups assert that VISTAS' modeling
and source selection process was arbitrary and capricious and
unreasonably excluded the following eight ``significant'' sources that
``likely contribute to impairment at one or more Class I areas with a
[cumulative] Q/d of 5 or more''--Williams Station (Q/d of 209.65),
Wateree Station (Q/d of 8.98), Cope Station (Q/d of 6.99), Sylvamo Mill
(Q/d of 191.18), Argos Plant (Q/d of 54.87),\57\ Holcim Plant (Q/d of
132.82), New-Indy Plant (Q/d of 115.29) and WestRock-Florence (Q/d of
84.8). They state that EPA's proposal does not evaluate emissions from
any of these eight sources and that there are likely reasonable and
cost-effective controls available for these sources that would be
necessary to make reasonable progress.
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\57\ The comment appears to erroneously use the cumulative Q/d
value from the ``Argos Cement'' facility in Shelby County, Alabama.
According to the NPCA's Regional Haze Interactive Map (2024), the Q/
d for Argos Plant (labeled as ``Harleyville Cement Plant'' on the
map) should be 54.87, instead of the 5.49 originally stated in the
comment. See <a href="https://experience.arcgis.com/experience/46dd650b65284b64bf38ccba0e90af8b/?org=npca">https://experience.arcgis.com/experience/46dd650b65284b64bf38ccba0e90af8b/?org=npca</a>.
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The Conservation Groups further assert that Williams Station is
very close to Cape Romain and the scrubber and selective catalytic
reduction (SCR) systems can likely be cost-effectively optimized or
upgraded. For Sylvamo Mill, they contend that South Carolina excluded
the source because it discontinued burning coal in one of its boilers
even though there are no restrictions on any of the boilers that
prohibit the use of coal. For the New-Indy Plant, the Conservation
Groups state that according to the USFS, the plant is the largest
source in South Carolina contributing to visibility
[[Page 57660]]
impairment at multiple Class I areas in North Carolina and Georgia.
They claim that the plant contributes over 38 percent of South
Carolina's emissions that impact Linville Gorge, over 26 percent of
South Carolina's emissions that impact Shining Rock, over 19 percent of
South Carolina's emissions that impact Cohutta, and nearly 13 percent
of South Carolina's emissions that impact Joyce Kilmer.
Response 9.a: EPA disagrees that the Agency must require South
Carolina to conduct FFAs for Williams Station, Wateree Station, Cope
Station, Sylvamo Mill, Argos Plant, Holcim Plant, New-Indy Plant, and
WestRock-Florence. These sources did not exceed South Carolina's source
selection thresholds, and EPA has determined that the State's source
selection methodology is reasonable. See Responses 7.a and 8 for
further discussion.
The assertion that the Q/d values for these eight sources are
greater than five appears to be the overarching basis for the
Conservation Groups' argument that South Carolina unreasonably excluded
these sources from FFAs. However, as discussed in Response 7.g, the use
of Q/d (which simply involves dividing the quantity of emissions by the
distance to a Class I area) does not consider transport direction/
pathway, dispersion and photochemical processes, or the particular days
that have the most anthropogenic impairment due to all sources. When
compared to photochemical modeling, using a simple Q/d technique would
have resulted in a less accurate quantification of visibility impacts
on Class I areas. EPA has determined that the State's source selection
methodology is reasonable for the reasons discussed in the NPRM and
this notice of final rulemaking (NFRM). See Responses 7.a and 8 for
further discussion.
Regarding the specific comments about Williams Station, Sylvamo
Mill, and New-Indy Plant, again, these sources were not selected for
further analysis, and EPA agrees with the State's source selection
methodology. See Response 9.
Comment 10: The Conservation Groups assert that South Carolina
unreasonably refused to conduct an FFA for Winyah on the basis that it
is effectively controlled. The Conservation Groups argue that the plain
language of the CAA and RHR do not allow EPA or the State to eliminate
sources from analysis based on the assertion that sources are
``effectively controlled.'' Instead, they comment that the CAA and RHR
require states to consider the four statutory factors for any existing
source that is reasonably anticipated to cause or contribute to any
impairment of visibility in any Class I area and determine the emission
reduction measures necessary to make reasonable progress. They state
that the RHR and CAA require South Carolina to develop a LTS ``that
addresses regional haze visibility impairment'' for each affected Class
I area, and that flexibility in recent EPA guidance does not override
the CAA and the RHR. They contend that South Carolina failed to conduct
FFAs for EGUs such as Winyah despite their contribution to visibility
impairment. They assert that although Winyah exceeded source selection
thresholds, the State exempted the facility from an FFA by claiming it
had ``effective controls'' in place. The Conservation Groups claim that
the State therefore attempted to ``re-write''
[…truncated; see source link]Indexed from Federal Register on December 11, 2025.
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